1. Preheat oven to 425 °F. 
2. Mix together flour, sugar, and salt.
3. Melt margarine, then mix warm water into margarine.
4. Make a well in the dry ingredients and pour in the wet.  Mix with a fork until evenly combined.  You may add a splash more water if there is still some dry flour.  Do not over-mix.
5. Divide the dough into 9 chunks and cover them loosely with a sheet of plastic wrap so they don’t dry out.
6. Place paper baking cups in 9 of the muffin wells of your muffin tin.  Spray them lightly with non-stick pan spray.
7. Starting with your middle muffin cup, place your first chunk of dough into the cup and use your fingers to press the crust evenly up the sides and across the bottom.  You will not make it to the top of each baking cup, but try to get the sides to be about 1 inch tall.  Repeat this 8 more times with the other 8 pieces of dough.
8. Use a fork to poke the bottom of each crust 2-3 times.
9. Bake the crusts in the oven for 6 minutes.
11. While crusts are baking, prepare your mix-ins.
12. Remove crusts from oven.  Turn oven down to 350 °F.
13. Place your fully cooked mix-ins into the empty crusts.
14. Mix together the egg product, milk, salt, and pepper.  Pour egg mixture over the mix-ins, distributing it evenly throughout all 9 mini quiches.  Sprinkle cheese on top.
15. Bake for 20-25 minutes, until eggs have puffed up and toothpick comes out clean.  Note: depending on the mix-ins you choose, a toothpick may not come out completely clean (for instance, if there is cubed cheese inside).
16. Remove quiches from oven and allow to cool about 10 minutes.  Serve immediately, or remove paper baking cups from each quiche and allow them to finish cooling on a wire rack (to avoid soggy bottoms).

Store leftovers in the fridge for up to 4 days, or in the freezer for up to 1 month.