1. Preheat oven to 400°F/200°C.  Line baking two baking sheet pans with parchment paper or a silicone mat and set aside.
2. Make pâte à choux dough.
3. Fill a pastry bag fitted with a 1/2-inch star tip* with the dough.  Pipe thirty 2-inch circles on the prepared baking sheet pans, allowing for 2-inches between each Paris-Brest.  Brush each pastry with a bit of egg wash and sprinkle with sliced almonds.
4. Bake, one sheet at a time, in preheated oven for 10 minutes, until pastries have risen.
5. Lower the oven temperature to 325°F/160°C.  Bake for an additional 35-40 minutes.  The Paris-Brest should be golden brown and fully baked on the inside.  Allow pastries to cool completely on a wire rack.

For the almond cream filling

1. Line a sheet pan with plastic wrap and set aside.
2. In a medium saucepan, combine 3/4 cup (170 g) of the milk, the 2 tablespoons (25 g) butter, 2 1/2 tablespoons (32 g) of the sugar, the vanilla bean seeds and the vanilla bean pod.  Set over medium heat and bring to a boil.
3. Meanwhile, in a medium bowl, whisk together cornstarch, all-purpose flour, and remaining 2 1/2 tablespoons (32 g) granulated sugar.  Whisk in the remaining 1/4 cup (56 g) of milk.  Whisk in egg yolks until combined.
4. Once boiling, take the vanilla mixture off of heat and remove vanilla bead pod.  Pour half of the milk mixture into the egg mixture while whisking vigorously to prevent the egg yolks from cooking.  Pour the egg mixture through a sieve into the saucepan with the remaining vanilla mixture.
5. Return saucepan to medium heat and bring pastry cream to a boil while whisking constantly.  Allow to cook for 1 minute and then remove from heat.
6. Transfer pastry cream to the plastic-lined sheet pan.  Spread mixture into an even, thin layer.  Place plastic wrap directly on top and refrigerate until cool to the touch.
7. Place the pastry cream in the bowl of a stand mixer fitted with the whisk and whisk on high speed for about 1 minute.  Add the remaining 6 tablespoons (85 g) softened butter and almond butter to the bowl.  Lower mixer to medium-high speed and mix for an additional minute.  Scrape down the sides of the bowl to ensure evenly mixed.  Continue to whisk for another minute on high.  Transfer filling to a pastry bag fitted with a 1/2-inch star tip.

Assembling Paris-Brest

1. Using a serrated knife, slice each Paris-Brest in half horizontally.
2. Pipe filling onto the bottoms and place tops over the almond cream.  Refrigerate for 1 hour to allow the filling to set.  Add a light dusting of powdered sugar and serve.