Preheat oven to 350°F. In a 9 x 13-inch baking pan, combine tomatoes and jalapeño. Bake for 10 minutes. Mix well, smashing down the tomatoes a bit with a spoon or spatula to help them break down.
In a separate bowl, combine remaining ingredients. Mix well and pour over tomatoes in the pan. Mix again to ensure everything is well coated.
Return pan to oven and bake for 25-30 minutes, stirring halfway through the baking time. You want the tomatoes to be soft, jammy, and starting to caramelize a little around the edges.
Let cool, then transfer to a container. Store in the fridge for a few days—or freeze for later. This tastes even better the next day.