1. Preheat oven to 350°F. Coat large loaf pan with olive oil cooking spray. Bring 1/2 cup oats, 1 tsp. garlic, bay leaf, and 1 cup water to a boil in saucepan. Reduce heat to medium-low, cover, and cook 10 minutes, or until oatmeal is thick, stirring occasionally. Remove from heat, remove bay leaf, and set aside.
2. Heat oil in large skillet over medium heat. Add onion, and sauté 3 to 5 minutes, or until translucent. Add herbes de Provence and remaining 1 tsp. garlic, and sauté 1 minute more. Add chopped tomatoes and juice. Crumble tempeh into mixture, and stir in vinegar and sugar. Season with salt and pepper, if desired.
3. Transfer tempeh mixture to food processor, add cooked oatmeal, and blend until combined. Add remaining 1 1/2 cups oats and baking powder, and pulse until combined.
4. Spread oat mixture in prepared loaf pan. Spray top with olive oil cooking spray, and pour marinara sauce over top. Bake 50 minutes to 1 hour, or until top begins to brown and marinara sauce is hot and bubbly.