pie crust crumb
1½ cups flour
2 tablespoons sugar
¾ teaspoon flaky salt
½ cup butter, melted
1 ½ tablespoons water
Heat the oven to 350° F.
Combine the flour, sugar, and salt in the bowl of a food processor. Add the butter and water and pulse several times until the mixture forms small clumps.
Spread the crumbs evenly on a parchment-lined pan. Bake for 20-25 minutes, tossing them occasionally. They are done when they are golden brown.
Let the crumbs cool completely before using in a recipe or eating. Stored in an airtight container, the crumbs will keep fresh for 1 week at room temperature or 1 month in the fridge or freezer.
pie crust frosting
adapted from Martha Stewart
6 tbs unbleached all-purpose flour
1 ½ cups whole milk
1 teaspoon pure vanilla extract
1 ½ cups butter room temperature
1 ½ cup sugar
½ recipe of pie crumbs, pulverized to a fine powder
Cook milk and flour in a small saucepan over medium heat, whisking constantly until the mixture thickens to a gluey, pudding consistency. Cover the pan and cool to room temperature. It needs to be completely room temperature before the next step or it will melt the butter. At this point you can chill this mixture to make the frosting later, but if you do, do not proceed before bring back up to room temperature - cold flour mix added to butter will seize and split the frosting.
In a stand mixer with the paddle attachment, whip together butter and sugar on medium speed until light and fluffy, about 5 minutes. Add in room temperature milk mixture and increase speed to medium-high. Whip until the mixture is smooth and very fluffy, which can take more than 15 minutes sometimes. It may look split or grainy or weepy at some point, but just keep on mixing until fluffy and velvety. This always takes way longer than I think it should, so I recommend that you walk away at this point and don’t look at the frosting more often than every 5 minutes. I like to use this time to do some of the dishes I have made or have a snack. Just don’t stare at your frosting getting stressed out.
When you have smoothness and fluffiness, add the vanilla and beat until fully incorporated. Add the pie crust crumbs and beat to incorporate.
If your frosting becomes a little soft and droopy at any point, chill it in the fridge for about 10 minutes, and the beat again. Repeat until frosting is smooth and holds a peak.
apple filling
2 medium Granny Smith apples, peeled and thinly sliced
1 tablespoon butter
⅔ cup light brown sugar, tightly packed
½ teaspoon ground cinnamon
¼ teaspoon kosher salt
Cook all ingredients in a small saucepan until the apples are tender but not mushy. If liquid is still very thin, remove apples and continue to reduce until syrupy and about half of the original volume. Toss with apples.
apple cider soak
Combine all ingredients in a plastic squeeze bottle. Chill until ready to use.
salted caramel drizzle
adapted from sally's baking addiction
Melt sugar in a pan over medium heat, stirring until fully dissolved. Continue stirring constantly until sugar is deep gold. Add butter and stir until incorporated into sugar. Still stirring, add cream in a slow stream. Sugar will bubble up. Continue cooking for one minute and then remove from heat.
The caramel can be made in advance and stored in the fridge.
assembly
Level cake layers and trim off the sides if you like - I like to because sometimes the sides are a bit more cooked than I want them. Drizzle cake with apple cider, either in a plastic squeeze bottle or with a pastry brush. You want to get good, even coverage without totally soaking your cake.
Place a cake board, if using, or a very flat plate, onto a cake turntable. Put a layer on cake on the board and scoop on a generous layer of frosting. Spread evenly over the cake and drizzle caramel overtop (a plastic squeeze bottle comes in handy here too). Sprinkle on a little of the remaining pie crumbs (about ¼ remaining crumb). Repeat layering cake, frosting, caramel and crumbs with the middle layer, and top with the final cake layer.
Give the whole cake a quick overall frosting, making sure to cover the sides and top entirely. Don’t worry about making it smooth at this stage, just frost it quickly. Put the cake in the fridge about 20 minutes.
Remove from the fridge and frost again, this time taking care to smooth the sides and top, using a generous amount of frosting and then scraping off excess with a bench scraper or offset spatula. Chill again until frosting is very firm, about 30 minutes. Drizzle caramel overtop, dripping a little down the sides of the cake. Decorate the top with remaining crust crumbs. Chill the cake if not serving right away, but let it sit out for two hours before serving to come back to room temperature.