Roasted Canned Tomatoes - Crock Pot Style

I was feeling lazy with cooking the other day, but wanted a yummy tomato sauce to smother my chicken in. So I made THIS but used a crock pot instead of roasting them in my oven for a couple of hours on a hot summer day. It turned out REALLY tasty

2 28 oz cans peeled whole tomatoes, drained, halved, and seeded.
1/2 to 2/3 C extra-virgin olive oil
14 large fresh basil leaves, torn
2 4-inch branches fresh rosemary
1/2 medium red onion, cut into 1/4-inch dice
5 large cloves garlic, coarsely chopped
Salt and freshly ground black pepper

Throw it all together in a crock pot, stir until well mixed. Cook on high for 4 hours, or low for 6-8 hours. Serve over chicken, rice, pasta, or anything else.