Roasted Broccoli Rabe and Pesto Flatbread

packed fresh basil

sliced almonds, plus more for garnish

grated Parmesan cheese

garlic, roughly chopped

lemon juice (about ½ lemon), plus more for garnish

salt

Freshly ground black pepper

extra-virgin olive oil, plus more for the broccoli rabe

whole grain naan flatbreads, about 7 inches in diameter

(about 3¾ ounces) crumbled feta cheese

broccoli rabe (about ¼ pound)

Red pepper flakes, for garnishing