For the pie crust, in a large bowl, whisk together the flour, sugar, and salt. Using the large holes of a box grater, grate the butter into the dry ingredients. With a fork, toss the butter and flour mixture until the butter pieces are all evenly coated with flour. Don’t break down the butter pieces in this step, just lightly toss until they are coated with flour.
Add the sour cream. Using the same fork, mix the sour cream into the butter/flour mixture by pressing the fork down into the sour cream in order to mash the large clumps of sour cream into the flour and butter. After a few turns with the fork, it is easiest to use your hands to pull the dough together. It will look a bit shaggy, but as you press it together (quickly and firmly so the the butter pieces don’t melt), it should start to form a cohesive ball. If it still seems overly dry, add a tablespoon of ice water. It’s ok if there are still a few dry spots or cracks in the dough.
Press the mixture into a thick disc and cover in plastic wrap. Refrigerate for at least 30 minutes or up to several days.
Roll out the pie crust on a lightly floured counter or on a pastry cloth/board to about 1/8-inch thick. Using a 2-inch cookie cutter, cut 12 circles (use a larger cookie cutter if you want the crust to go higher up the sides of the pan - there should be enough crust for slightly larger circles). Press each circle lightly into a lightly greased 12-cup muffin tin.
Preheat the oven to 375 degrees F.
For the egg mixture, in a medium bowl, whisk together the eggs, cream, milk, salt, pepper, and garlic powder until well combined.
Divide the ham and cheese evenly among the muffin cups (can also sprinkle a few green onions or chives in right now if you want them baked into the quiches).
Spoon the egg mixture over the ham and cheese, filling about 2/3 to 3/4 full. Bake for 15-18 minutes until set. Remove from the oven and sprinkle with green onions or chives, if desired. Serve warm or at room temperature. I find it's easiest to remove them from the muffin tin once they are mostly cooled; run a sharp knife around the edges before removing.
Notes
Substitutions: you can adapt the quiche fillings depending on your preference or what you have on hand. For instance, you can use cooked bacon or sausage instead of ham...or leave them meatless. You can also vary the cheese (Swiss, pepper jack...lots of options!). Try adding veggies, if desired! You can also try omitting the milk and using all heavy cream (1/2 cup total) for a richer version or omit the cream completely and use all milk (1/2 cup total) for a bit lighter version.For the Pie Crust: you can sub in a favorite pie crust recipe of your own (although the pie crust included in this recipe is divine and easy to make), or you can use storebought pie crust - it just needs to be enough to cut out twelve 2-inch or slightly larger circles.Make Ahead:The mini quiches can be made ahead of time, cooled and refrigerated. I like to reheat them in a 200 degree oven until just warm and then serve.