Preheat the oven to 375ºF when you're ready to bake.
Start by making your pie crust. Mix together flour, salt and sugar. Using a stand mixer fitted with a pastry hook or by hand using a pastry cutter, add butter or lard. Room temperature works fine or cold and cut into cubes. Slowly add in water a little at a time until dough is crumbly but sticks together when you squish it with your hands. If you need to add more water, add in 1 tbsp at a time.
Roll dough into a ball and divide into two portions. Roll each portion into a ball and flatten into about a 1-inch thick disc. Wrap and refrigerate about an hour until firm.
Wash, pit and stem your cherries. Add sugar, lemon juice, cornstarch and cinnamon to cherries and mix well to combine. Cover and set aside.
Remove dough from the fridge and unwrap. Roll out each round of dough onto a floured surface to about ¼-inch thickness. Cut out 12 smaller rounds with the band from a wide mouth Mason jar or cookie cutter of similar size. Roll each small round out to about 5 or 6 inches in diameter. Fit each round into a greased muffin tin and allow about ¼-inch of crust to overhang.
Fill each pie crust with cherry filling. Make sure it's heaping but not overflowing the edges of the crust.
Roll out the other half of your pie crust and cut 12 more rounds and roll them out just like the last batch. Decide how you want to top your pies. Cut into a lattice or place your whole pie crust on top and cut slits. *Before placing your top crust on, mix together egg yolk and water to make an egg wash. Brush this on the edges of your bottom pie crust before placing your top crust on to help it stick.
Press edges down with a small fork and trim any excess crust from the edge with a small kitchen knife. Brush the tops with remaining egg wash and sprinkle with a little sugar. Pop them in the oven and bake for 25-30 minutes. Let cool and enjoy.