1. Melt the butter with the oil in large skillet over medium-high heat. Add the garlic and cook, stirring, for 10 seconds. Add shrimp, season with salt and pepper, and cook, stirring, until just opaque throughout, about 2 minutes. Remove from the heat.
2. Toast the bread slices in a toaster oven or oven. Top each with 3 to 4 shrimp and drizzle with the pan sauces. Grate the lemon zest directly over the shrimp, then squeeze some lemon juice on top. Serve immediately.