Heat 1/2 cup olive oil in large, heavy-bottomed saucepan over medium heat. Add the 2 crushed garlic cloves, cauliflower and shallot and cook, stirring often, until the cauliflower begins to soften and the shallots begin to caramelize slightly, 7 to 8 minutes. Add the chickpeas and continue to cook, stirring often, until everything is well combined and the chickpeas are heated through but still hold their shape, another 5 minutes. Remove from the heat and set aside.
Brush a rimmed baking sheet with 3 tablespoons olive oil. Gently stretch the pizza dough to fit the pan. (If the dough shrinks back, let it rest a few more minutes before stretching again.)
Spoon the cauliflower mixture evenly over the dough.
Bake until the crust is golden brown and the cauliflower is browned in some spots, about 15 minutes.
Meanwhile, slice the jalapeno in half crosswise and remove the seeds if you'd like less heat. Roughly chop the bottom half and thinly slice the top half into rounds.
Combine the chopped garlic clove, chopped jalapeno, cilantro, lemon juice, remaining 1/4 cup olive oil, 1/4 teaspoon kosher salt and few grinds black pepper in a blender and puree until smooth. (If necessary, stop the blender and scrape down the sides with a rubber spatula to help everything blend.)
Transfer the flatbread to a cutting board and drizzle with the cilantro sauce. Top with the jalapeno rounds, a squeeze of extra lemon juice and a pinch of flaky salt.
To make shaping the dough easy, keep the dough refrigerated until 10 to 15 minutes before you are ready to use it. You may find that stretching it a bit, and then allowing it to sit 15 minutes more makes it even easier to shape.