Heat your oven to 350 degrees.

Slice the tomatoes, and spread them out in a single layer on a parchment-lined baking sheet. The parchment is important because it prevents the tomato juices from burning, and the parchment makes it easy to transfer those juices into the blender.

Drizzle 1 ½ tablespoons of olive oil over the tomatoes, and then sprinkle with the salt and pepper.

Tear a small sheet of aluminum foil. Then cut the root end off of the head of garlic. Place it on the foil, sliced-side facing down. Drizzle the remaining olive oil over the garlic, then wrap it up in the foil. Place it on the baking sheet with the tomatoes.

Roast the tomatoes and garlic for 30 minutes. Then remove them from the oven. Unwrap the garlic to let it cool. Place the tomatoes and all of their juices in a blender and liquefy.

Add cloves of garlic to taste, and liquefy again. Finish by adding additional salt and pepper to taste.