1 9" tart crust, par-baked
~ 1 1/2-2 cups cherry tomatoes (the exact amount may vary, depending upon the size and shape of your tomatoes - if you roast too many, that's not a bad thing at all)
1 Tbsp dijon mustard
8 oz soft goat cheese, such as chevre
1/2 cup half-and-half or milk
2 tsp chopped fresh thyme (or other herb of your choice), divided
Preheat the oven to 200 degrees. Halve the cherry tomatoes along their equators, and place them cut-side up in a baking dish. Drizzle with a bit of olive oil, and place them in the oven for 3 hours. They should shrink up somewhat, to maybe 2/3 their size, but still be juicy. Set aside.
Raise the oven temperature to 375 degrees. Spread the mustard along the bottom of the tart shell, leaving a very thin layer. In a mixer (or using a whisk or fork and a lot of patience), blend together the goat cheese, eggs, half-and-half, and half the fresh herbs. Pour this mixture into the tart shell. Gently place the tomatoes on top, cut-side up, in an arrangement that strikes you.
Gently transfer the tart to the oven, and bake ~45 minutes, until the filling has puffed and begun to brown, and the tomatoes are caramelized a touch on top. Remove from the oven and let cool slightly. Sprinkle the remaining fresh herb and a light sprinkling of salt across the top, and serve.