I got this, basically, from the Everyday Foods magazine by Martha Stewart. I wasn't able to follow her directions exactly with what I had on hand so I used what I did have. And boy howdy, lemme tellya - I got addicted - I blended a bit of this up w/ some water to make an impromptu spaghetti sauce, but the way I liked it best was on cheesy bread - bread w/ cheese on top baked in the oven til the cheese was melted and the crust was crusty. (I used a croissant w/ provolone once, another time I used plain ole whole wheat bread w/ shredded cheddar. Each time was delish.)
3 cans diced tomatoes (14oz. ea) - you really should use more to make more, but I only had 3 on hand.
3 smashed garlic cloves (mine were so smashed I was able to scatter the tiny pieces throughout the tomato mixture)
3 Tbs. olive oil.
Preheat oven to 400 deg.
Pour the diced tomatoes onto a cookie sheet, dot with crushed garlic and drizzle the olive oil on top. Season with a bit of salt, pepper and crushed, dried oregano, if using. Roast 45 minutes, turn pan (I gave it a little stir at this point but I don't think you have to), then roast another 30-45 minutes until its all thick. Either use right away or let it cool and refrigerate (up to a week).