Place flour, baking powder, and salt in food processor and pulse 3 times.
Add butter and run the food processor until mixture resembles breadcrumbs.
If you don't have a food processor, whisk flour, baking powder and salt in a medium-size bowl.
Rub in butter with your hands until the mixture resembles coarse meal.
Gradually add in milk just enough to form a soft dough. You may need to use less or slightly more than a 1/2-cup.
Lightly grease a baking sheet with cooking spray; set aside.
Flour your work area and knead the dough for a minute.
Roll it out and form a 10-inch round.
Place dough on prepared pan; set aside.
Preheat oven to 425.
Heat olive oil in a pan and add garlic, onion, and zucchini.
Season with salt and pepper.
Cook for a few minutes, or until softened, stirring occasionally.
Remove from heat.
Spread pizza sauce on dough.
Add drained diced tomatoes.
Top with zucchini mixture.
Sprinkle the goat cheese over zucchini.
Bake for 20 to 25 minutes, or until pizza dough is golden brown.
Cut and serve.