Brush 1 tablespoon of the olive oil all over the bottom of the baking sheet. Sprinkle on the dried basil, black pepper, and kosher salt.
Place the tomato halves face down on the baking sheet, keeping them close together. Scatter the peeled garlic cloves amid the tomatoes. Drizzle on the remaining olive oil and add a little more pepper if desired.
Roast in the preheated oven for about 8 hours. The tomatoes will shrivel and caramelize a bit. Remove from the oven and cool completely. Slip the skins off and put the tomatoes plus any pan drippings in the small freezer containers. Top each container with a little more olive oil, then seal tightly and freeze. Will keep for up to 6 months.