Step 1

Heat the oven to 375°F (190°C) with a rack in the lower third (preferably with a baking steel or stone on it).

Step 2

In a medium bowl, whisk the sugar and flour to combine. Add the brown sugar and mix to combine. Whisk in the milk, cream, vanilla extract, and salt, and mix just to combine—too much whisking will lead to lots of air bubbles that can linger on the surface of the custard after you transfer it to the crust. Gently whisk in the pumpkin puree and pumpkin pie spice until incorporated.

Step 3

Place the parbaked crust on a parchment-lined baking sheet and pour in the custard (pour any that doesn’t fit into a separate ramekin and bake). Bake until the filling appears set at the edges but is still jiggly in the center, 28 to 32 minutes. (In a deeper pan this can take much longer, even 45 minutes to an hour.) Cool to room temperature, then chill for at least 2 hours, or until ready to slice and serve.

Step 4

In the bowl of a stand mixer fitted with the paddle attachment (or if you don’t have an electric mixer, feel free to mix in a bowl with a wooden spoon or silicone spatula), cream the butter and sugar on medium-low speed until smooth, 2 to 3 minutes. Add the egg yolk and vanilla, if using, and mix on medium speed to combine. Scrape the bowl well. Add the flour and salt and mix on low speed until fully incorporated, 45 seconds to 1 minute. Add the water and mix just until the dough is smooth, about 1 minute more. If the filling still looks dry or crumbly, you can add a few more drops of water until it holds together when pressed.

Step 5

Turn out the dough and use your fingers to press it evenly into the pan or pans—this crust will hold a shape if you crimp it, but it also looks nice just flattened evenly to the edges. Chill for at least 30 minutes, and up to overnight.

Step 6

This crust is best baked at 350°F (175°C). To parbake the crust: Bake, without pie weights, for 15 to 18 minutes, until the crust is beginning to turn lightly golden. If the bottom crust starts to puff up, you can poke the bottom with a fork in a few places to deflate it, and continue baking (the egg wash will seal the holes). To use with the pumpkin sugar pie filling: Remove the pan from the oven, brush the bottom and sides with egg wash (any egg wash is fine, but here, your leftover egg white works perfectly!), and let cool completely in the pan.