Preheat the oven to 450 degrees F (235 degrees C).
Divide pie dough into 6 equal portions, and roll out each portion into a 5-inch circle.
Line each cup of a 6-cup standard muffin pan with a pie crust circle, and lightly prick the bottoms and sides with a fork. Use a fork dipped in flour to flute the edges, if desired.
Combine beaten egg with water and stir well. Brush crusts with a little egg wash, reserving the unused portion. Place muffin tin on a cookie sheet
Bake in the center of the preheated oven until the crust is a little puffy and light golden brown, 10 to 12 minutes. Remove from the oven and allow to cool slightly. Lower the oven temperature to 375 degrees F (190 degrees C).
For filling, combine remaining egg mixture, diced tomatoes, basil, garlic powder, and red pepper flakes. Season with salt and pepper.
To assemble tarts, place 1 tablespoon shredded cheese in the bottom of each tart shell. Evenly divide tomato mixture among the tarts, and top each tart with crumbled bacon.
Return tarts to the oven and bake until the filling is set and the crusts are brown, about 20 minutes. Remove from the oven, and allow to cool on a rack about 5 minutes. Free the edges of the tarts by slipping a fork or a small offset spatula between the tart and the muffin tin, until they move freely. Gently remove the tarts from the muffin tin to a serving plate.
Garnish with green onion slices and serve warm, or at room temperature.
