Meanwhile, add about 1 tablespoon olive oil to a skillet over medium-high heat. Cut chicken breast into two-inch (bite-sized) pieces. Season with sea salt and black pepper, then squeeze lemon juice over top, and add lemon zest and half the garlic.
Cook chicken breast in olive oil until cooked through (about 6 minutes). Remove from pan and set aside.
Turn heat down to medium and add a bit more olive oil to pan. Cut your tomatoes into halves then add them to pan with remaining garlic and crushed red pepper to pan.
Allow tomatoes to cook down for about two minutes or until the skin is very glossy and starts to wrinkle. Stir in spinach and cooked until wilted (about 3 minutes).