Slab Pie - Blueberry and Strawberry Rhubarb

Isn't the name of this one great? I just had to make "slab pie" for the Fourth. Had to. If you are looking to feed a lot of people, make this. It's basically fruit pie baked up in a large rectangular pan. It feeds an army (anywhere from 16-24) and is highly portable so it's much more convenient to bring this to a party or pot luck than a sweet little 9"pie that only serves eight. When this is done, you drizzle the crust with a simple glaze and cut into squares. It looks like a huge pop tart, so who wouldn't like that? The crust is made with all butter which yields a flaky almost pastry like crust which makes for a flexible but sturdy base so you can actually pick up the squares and eat them with a napkin...no plate necessary. Pie in the hand? Awesome.

I made my fillings with a blueberry and strawberry rhubarb, respectively, but feel free to use any fruit filling you like. Some tips for replacing the blueberries with other fruit: This pie is roughly 100% of a regular pie filling with 150% of the crust. If you are looking to use something besides the fillings provided, you could swap in 6 cups of any other fruit. Adjust the sugar accordingly because you would use less sugar for peaches or berries than you would, say, sour cherries unless you like your pies on the sweeter side. I used quite a bit of sugar for my blueberries, but they were on the tart side. Always try your fruit before you decided how much sugar to use. Adjust the cornstarch too, since different fruits give off varying amounts of liquid. Also, if you have a recipe you like for a fruit pie filling you can use that. Most recipes call for 6 cups of fruit for a standard pie which is how much you'll need for this recipe. That way you know your thickener and sugar is spot-on. Lastly, you could always make your life easier and use canned pie filling. I cannot believe I just suggested that. I suppose we all need a break sometime!

* New note: You can also make filling that doesn't have to be cooked and thickened before baked in the crust. Like a cherry or peach pie for example. Classically, you would just toss the fruit with a variety of spices and or sugar and some sort of thickener and put directly into the crust for baking. For peach pie try: 6 cups of chopped peaches, 2 tablespoons flour, 1/2 cup granulated sugar, 1/2 cup brown sugar, 1 teaspoon lemon juice, 1/2 teaspoon cinnamon, 1/2 teaspoon vanilla. Toss everything together just before pouring into the crust. You don't want to do it ahead of time because the peaches will get too juicy sitting in the sugar. For cherry pie try: 6 cups pitted sour cherries (fresh or frozen will work; if frozen, defrost and drain first)1 cup sugar, 1/4 cup cornstarch, juice of half a lemon and a pinch of salt. Combine everything and pour into the crust and bake.

A quick note for people who don't have much experience with cooking a pie filling. I'm a visual person, so I figure pictures will help ensure success. The instructions ask that you cook a cup and a half of the fruit (take note: this is only a small amount of the fruit. You will have fruit left over to mix in later) with the sugar and simmer until all the sugar is dissolved. This might sound wrong since there is no liquid in the pan. Don't worry, the berries will break down a bit and the sugar will melt over low heat, giving you something that looks like this:

Keep cooking until it the sugar has all melted and become juice. It looks something like this:

After that, you will be asked to add the cornstarch dissolved in a little water to your filling. Then you will cook said mixture, stirring constantly, until it has thickened, is bubbling and is no longer cloudy, but clear. This is sort of deceiving. You have to cook this mother a while. Like 10-12 minutes or so. It will slightly thicken up after a few minutes, but if you cook it longer, it will thicken even more. Cook until you have the consistency of syrup. It should look something like this:

Now you can add the rest of the ingredients:

Then, and only then, can you add the rest of the berries and fruit to the mix. The pie crust is easy to make. Don't let anyone tell you it's not. The dough itself is pliable and soft, making it easy to roll out thinly.

The finished product:

Slab Pie

adapted from smitten kitchen

serves 20-24

Blueberry Slab Pie

1 recipe All Butter Really Flaky Pie Dough, (recipe below) divided patted into thick rectangles, wrapped in plastic and chilled for at least an hour in the fridge.

6 cups fresh blueberries

1 to 1 1/4 cups sugar

7 tablespoons cornstarch

5 tablespoons water

1 1/2 teaspoon lemon juice

1/2 teaspoon ground cinnamon

2 tablespoons unsalted butter

Glaze:

1 cup confectioners sugar

1 to 2 tablespoons milk

To make the blueberry filling: combine 1 3/4 cup of the blueberries with the sugar in a nonreactive saucepan. Bring to a simmer over low to medium-low heat, stirring occasionally, until the sugar is melted and the mixture is very liquid, about 5 minutes.

Combine the cornstarch and water in a small bowl and whisk the blueberry and sugar mixture into it. Return everything to the pan and cook, stirring constantly, over low heat, until the mixture comes to a boil, thickens and becomes clear-ish (not cloudy). If it does not become clear, continue to cook over low heat for a few more minutes, until it does.

Stir in the remaining filling ingredients except for the blueberries, then add the remaining berries and cool.

Strawberry Rhubarb Filling:

1 recipe All Butter Really Flaky Pie Dough (recipe below)

3 cups strawberries, hulled and sliced

3 cups rhubarb, trimmed and cut into 1/2-inch pieces

7 tablespoons cornstarch

5 tablespoons water

1 1/4 cups sugar

1 1/2 teaspoon lemon juice

1/4 teaspoon vanilla extract

1 tablespoon quick-cooking (instant) tapioca

2 tablespoons unsalted butter, cut into small pieces

To make the Strawberry Rhubarb filling: combine the strawberry and rhubarb in a bowl. Measure out 1 3/4 cup of the fruit and combine it with the sugar in a nonreactive saucepan. Bring to a simmer over low to medium-low heat, stirring occasionally, until the sugar is melted and the mixture is very liquid, about 5 minutes.

Combine the cornstarch and water in a small bowl and whisk the fruit and sugar mixture into it. Return everything to the pan and cook, stirring constantly, over low heat, until the mixture comes to a boil, thickens and becomes clear-ish (not cloudy). If it does not become clear, continue to cook over low heat for a few more minutes, until it does. It might still be slightly milky with this filling and that's okay.

Stir in the remaining filling ingredients except for the strawberries and rhubarb, then add the remaining strawberries and rhubarb and cool.

To assemble the pie: Preheat the oven to 350 degrees. On a lightly floured surface, roll out one of the dough halves into an 18-by-12 inch rectangle. I won't lie: this can be kind of a pain because it is so large. Do your best to work quickly keeping the dough as cold as possible.

Transfer to a 15-by-10-by-1-inch rimmed baking sheet, (pastry will hang over the sides of the pan). I went ahead and lined mine with parchment, just to ensure I'd be able to easily lift it out. Pour blueberry filling into lined baking sheet; set aside.

On a lightly floured surface, roll out remaining piece of dough into a 16-by-11-inch rectangle. Drape over filling. Bring bottom pastry up and over top pastry. Pinch edges to seal. If need be, rip off pieces of dough from places that could spare some and pinch it together to patch holes or bald spots in other places. Using a fork, prick top crust all over and brush with heavy cream or egg wash.

Bake until crust is golden and filling is bubbling, 40 to 55 minutes. Transfer to a wire rack and cool until just warm tot he touch, about 45 minutes.

In a medium bowl, stir together the confectioners sugar and milk until desired glaze consistency is achieved. Use a spoon to drizzle over top.

Cool the pie for 3-4 hours before cutting. The filling needs time to cool and set up.

All Butter Really Flaky Pie Dough

adapted from smitten kitchen

makes enough dough for one slab pie

3 3/4 cups all purpose flour

1 1/2 tablespoons sugar

1 1/2 teaspoons salt

3 sticks unsalted butter, very cold

1 egg, beaten with 1 tablespoon water, for an egg wash.

Fill a one cup liquid measuring cup with water, and drop in a few ice cubes; set aside. In the bowl of a food processor, pulse together the flour, salt and sugar until blended. Dice the butter into cubes and add it into the food processor. Pulse a few times until the butter is incorporated and is about the size of peas. Next, remove the ice cubes from your measuring cup and pour out some water so it is holding exactly 1 cup. With your machine running, slowly pour 3/4 cup of the water through the chute. Then, very slowly, add the remaining water about a teaspoon at a time just until the dough comes together and forms a ball. Dump the dough out onto a floured surface and knead to incorporate everything. If you have added too much water and the dough seems tacky, sprinkle some flour over the top and knead it in until it is no longer wet. On the other hand, if your dough is falling apart because it is too dry, add some water, a tablespoon at a time and knead until it comes together. You will probably not need the whole cup of water. I had a couple tablespoons left over every time.

Divide the dough in half, and place each half on a large piece of plastic wrap. Shape dough into a rectangle and wrap up. Place dough in the refrigerator for one hour before rolling it out. The dough will keep in the fridge for about a week, but if you don't plan on using it the day it's made, wrap it double in plastic wrap to protect the dough from refrigerator smells.