Question: Ottolenghi's very full roasted vegetable tart
I would just leave the roasted peppers out. There's plenty else going on in the tart, and you'll still get the sweet note from the roasted sweet potato. I used evaporated milk in place of the heavy cream; works just fine, still tastes great.
One note: don't use a standard loose-bottom tart pan with 1-inch sides - it's not deep enough to hold everything. If you don't have a deep tart pan, I would use a 9-inch springform pan.
This is a scrumptious recipe.
As Caitlin said, you can just leave the peppers out or adjust for what you have on hand.
For the cream, I just used milk once and it came out fine. The next time, I used a mix and blended some soft feta into it with an immersion blender, and it came out way better than expected.