Preheat the oven to 450 degrees F.
In a bowl, combine the flour, baking powder and salt, stirring to combine. Add the water and olive oil and mix with a spoon until the dough comes together. Use your hands to finish bringing it together into a ball, then knead it a few times on a floured surface.
Roll the dough into your desired shape – I rolled in into a long oval about 1/4-inch thick – you want it to be thin. Place it on a nonstick (or parchment papered) baking sheet and brush with a bit of olive oil. Bake for 10 minutes, until a few air bubbles form and the dough is golden.
While the crust is baking, heat a skillet over medium heat and add the chopped bacon. Cook until most of the fat is rendered, but the bacon isn’t fully crisped (this is important so it doesn’t burn in the oven!). Remove the bacon with a slotted spoon and place it on a paper towel to drain excess grease. Remove all but 1 tablespoon of bacon grease from the skillet.
Keep the heat under the skillet to medium-low and add the tomatoes and garlic. Add a pinch of salt and pepper. Cook, stirring often, until the tomato halves pop and soften, about 8 to 10 minutes. Turn off the heat.
Remove the crust and spread ½ to ¾ cup pimento cheese on top. Sprinkle on the bacon, tomatoes and scallions. Sprinkle on the extra handful of grated cheese. Bake for 10 to 15 minutes more, until the cheese is golden and bubbly. Remove and cover with the shredded lettuce. Slice and serve!