Place one tortilla on a clean, flat surface.
Sprinkle about one-quarter of the shredded mozzarella in an even layer over the tortilla.
On one half of the tortilla, arrange cooked crumbled pork sausage, five slices of pepperoni, and about 1 tablespoon of jarred mushrooms.
Lightly sprinkle the filled half with garlic powder.
Heat a 12-inch non-stick skillet over medium heat and coat lightly with cooking spray or a little oil or butter.
Carefully transfer the prepared tortilla to the hot skillet and cook until the cheese begins to melt, about 1 minute.
Fold the cheese-only side over the toppings to create a half-moon, then cook 1–2 minutes more, flipping as needed, until both sides are golden brown and crispy and the cheese is fully melted.
Remove from the skillet, cut into wedges, and serve warm with pizza sauce for dipping.