Congrats on hitting the mother lode of tomato harvests! I've been making a similar sauce for awhile, but I only roast the tomatoes and the garlic. Sometimes I roast carrots. I core and split the tomatoes, drizzle with olive oil, salt and pepper, whatever fresh herbs I have around. If there's room on the pan, I throw in some garlic, or peppers or carrots. After the tomatoes are giving up their juices (around 25-30 minutes), I dump them into a sauce pot in which I've sauteed more garlic, onions, and some rosemary. I like to deglaze the roasting pan to get the sticky bits - I use the heat from the sauce pot and put the roasting pan over like a lid.