Cook to Thicken:
Return the mixture to the saucepan and cook over medium-low heat, whisking continuously until thickened to a pudding-like texture (about 7–9 minutes).
Chill:
Transfer to a bowl, stir in vanilla, and cover with plastic wrap directly on the surface to prevent skin. Refrigerate until fully cooled.
Part 2: Make the Choux Pastry
Heat Butter Mixture:
Preheat oven to 425°F (220°C). In a small saucepan, melt the butter with water, sugar, and salt until simmering. Remove from heat.
Form the Dough:
Add flour and stir with a wooden spoon. Return to low heat and continue mixing for 1–2 minutes until the dough pulls away from the sides of the pan.
Add Eggs:
Incorporate the eggs one at a time, mixing well after each addition until smooth, glossy, and thick.
Part 3: Shape and Bake
Pipe the Ring:
Trace a 9-inch circle on parchment, flip the paper, and pipe or scoop mounds of dough along the line so they touch.
Bake:
Bake for 10 minutes at 425°F. Without opening the oven, reduce heat to 375°F and continue baking for 20–25 minutes until deep golden.
Dry and Cool:
Pierce each mound to release steam. Turn off oven and leave pastry inside with the door slightly open for 15 minutes. Cool completely.
Part 4: Assemble
Make Whipped Cream:
Whisk heavy cream until it begins to thicken. Add powdered sugar and vanilla, then beat to soft peaks.
Fill and Finish:
Slice the pastry ring horizontally. Fill the bottom with pastry cream, then pipe or spoon whipped cream on top. Replace the upper half and dust with powdered sugar.
