How to Make It
In a food processor, combine the butter, flour, baking powder and salt and pulse just until the mixture resembles coarse meal. Add the milk and pulse just until the dough comes together. Press the dough evenly over the bottom and halfway up the side of a 9-inch springform pan. Cover with plastic wrap and refrigerate until firm, about 45 minutes.
In a small bowl, whisk the chili powder with the cumin, 2 teaspoons of salt, the onion powder, cornstarch, cayenne and coriander. In a medium skillet, melt the butter. Add the ground beef and cook over moderately high heat, stirring, until browned and cooked through, about 5 minutes. Add the spice blend and 2/3 cup of water and cook, stirring occasionally, until the water has evaporated, about 3 minutes. Remove from the heat.
Preheat the oven to 350°. In a medium bowl, whisk the crème fraîche with the cheddar, egg and mayonnaise. Season with a pinch each of salt and pepper. Set the crust on a rimmed baking sheet. Using a slotted spoon, spread the ground meat evenly over the crust and cover with the cheddar topping. Bake until the topping is set and the crust is golden brown, about 45 minutes. Let cool for 15 minutes before serving.