
This Savory Apple Thyme Tart with caramelized onion and gruyere makes a wonderful vegetarian meal, especially when served alongside a simple green salad.
Meanwhile, make the filling: In a skillet over medium heat, melt the butter with the olive oil and swirl the pan to combine. Add the onions and cook until lightly browned and starting to caramelize, about 8 minutes per side. Remove from heat.