Paprika Roasted Leg of Lamb

Name: Paprika-Roasted Leg of Lamb
Ingredients: 3 tablespoons sweet paprika; 1 tablespoon pure chile powder, such as ancho or pasilla; 1 1/2 teaspoons ground cardamom; One 6 1/2-pound boneless leg of lamb, butterflied; 2 tablespoons extra-virgin olive oil; Salt; 6 whole garlic cloves; 4 rosemary sprigs; 2 thyme sprigs; 1 lemon, sliced 1/4 inch thick