STEP 1 Position a rack in lowest position of oven; preheat to 425°F. Line a large rimmed baking sheet with parchment paper or coat with cooking spray.
STEP 2 Roll out dough on a lightly floured surface to about the size of the baking sheet; transfer to the prepared baking sheet. Bake until puffed and crisped on the bottom, 8 to 10 minutes.
STEP 3 Meanwhile, cut chicken in half lengthwise and then crosswise into thin strips. Heat 3 tablespoons oil in a large skillet over medium-high heat. Add garlic and cook, stirring, until just starting to brown, 30 seconds to 1 minute. Add the chicken, broccoli rabe (or broccolini or broccoli), lemon zest, crushed red pepper and salt; cook, stirring, until the chicken is just cooked through, 4 to 5 minutes. Remove from heat.
STEP 4 When the crust is done, remove from the oven, flip it over and brush with the remaining 1 tablespoon oil. Using a slotted spoon (to help drain any excess liquid), transfer the chicken mixture to the crust and spread evenly. Combine ricotta and lemon juice and dollop all over the pizza.
STEP 5 Return the pizza to the oven and bake until the crust is crispy on the bottom, 6 to 8 minutes more.