Need a sensational vegetarian main dish? This galette with buttery pastry filled with roasted summer vegetables and a mustard cheese sauce is just the thing. Most of the time is hands off, while dough chills or tomatoes roast, and the dough and the sauce can be made ahead if you prefer.
The dough can be refrigerated for up to two days, or frozen for up to a month; thaw it in the refrigerator before using. The cheese sauce can be made ahead and refrigerated in an airtight container for up to three days (if it's too stiff to spread easily, rewarm it slightly before using).