The oven is heated to 200 ° C and It placed 4 refractory bowls (of 250 ml) with 1/4 of the oil in each. Heat for 2 minutes or until they are hot. During this time melt the butter with crushed garlic over low heat and stir shrimp in it, then remove from heat. Shrimp are distributed in warm bowls and bake in the oven for about 8 minutes or until shrink and change color. Serve in bowls, sprinkled with chopped onion.