Preheat your toaster oven to 400°F (can also use actual oven)
Peel and discard the papery outer layers of the whole garlic bulb, leaving intact the skins of the individual cloves of garlic. Using a sharp knife, cut a ½ inch from the top, exposing the individual cloves.
Place the garlic heads in a baking pan, cut side up. Drizzle with olive oil. Cover the bulb with foil. Bake 30 minutes. Allow garlic to cool before use.
Place basil, garlic, and pistachios into a food processor. Pulse until mixture is smooth. Once smooth, with the processor still running, slowly pour in the olive oil and lemon juice, Process until the mixture is smooth, you may need to scrape down the sides of the food processor. season with salt and pepper, to taste.