Preheat oven to 450F Line a baking sheet with parchment paper or foil.
Slice the garlic clove in half lengthwise and gently rub the cut side all over the tortilla. Lightly brush both sides of the tortilla with olive oil. Place it on your baking sheet.
Arrange your cheeses evenly over the pizza. I used a few thin slices of mozzarella, and few blobs of ricotta. There's no need to cover the whole surface. Then top with your mushrooms and onions. Again, be sparing.
Bake in a your preheated 450F oven for 15-20 minutes (depending on size,) until the cheese is melty and the crust is crisp and golden. Note: ovens differ, so check your pizza on the early side.
I like to very lightly drizzle a little more extra virgin olive oil on my pizza just as it comes out of the oven, and sprinkle it with a little sea salt and fresh cracked black pepper; this is optional. Slice and serve your pizza right away. One pizza is a perfect size for lunch or a light dinner for one. Cut into quarters for an appetizer.
The nutritional value is just an estimate, the exact values will depend on your particular ingredients and toppings.
Most parchment paper is oven safe to 450F. Read the label, or if unsure, use foil.