Whisk 3 eggs with 3/4 cup each flour and milk and 1 teaspoon kosher salt; let sit 5 minutes. Saute 6 thinly sliced garlic cloves and 1 tablespoon chopped rosemary in 6 tablespoons butter in a large ovenproof nonstick skillet, 1 minute. Add the batter and sprinkle with more rosemary. Bake at 425 degrees F until puffed and golden around the edge, 18 to 20 minutes. Sprinkle with sea salt.