Follow our recipe for kagecreme. It needs to chill completely before you can use it in this recipe. Alternatively, you could use any flavor of store-bought custard! Combine flour, powdered sugar, and salt in a food processor and pulse to combine. You can also do this by hand by whisking together the ingredients in a bowl!
Add cold butter and pulse in the food processor until it looks like sand. If doing this by hand, just break up the cold butter with your fingers and crumble until you reach a sand like consistency.
Add egg and vanilla extract and pulse until the dough starts to come together. If working by hand, add egg and vanilla to your bowl, mix to distribute, and gently press together until your dough forms a ball. Wrap the dough in plastic wrap and refrigerate for at least 30 minutes.
Butter a muffin tin thoroughly (you really don't want these to stick!). Preheat your oven to 375 degrees F (about 190 C).
Once your dough has rested, roll it out to about 1/8 of an inch thick (3 mm), and cut out circles. Keep in mind: the circles need to be larger than the bottom circle of each muffin hole in the muffin tin, since you also need to build the sides of the pies. Press these circles into the muffin tin and make sure your dough comes all the way up the sides.
Fill each pie with kagecreme, making sure not to overfill!
Then, cut out more circles, but this time slightly smaller, for the lids of the pies. Place them on top of the pies and connect to the sides of the pie by squeezing together the dough. You really want to make sure that the lid and the rest of the pie won't come apart in the oven!
Bake for 12-15 minutes or until golden brown. Enjoy!