8 prebaked individual tart shells (page 95)
1 tbsp extra-virgin olive oil
1 small onion, finely diced
Kosher salt and freshly ground pepper
H lb (250 g) butternut squash, peeled, seeded, and finely diced
1 tsp minced fresh sage
1 lb (500 g) Swiss chard, stems removed and leaves chopped
Pinch of sugar
1 cup (4 oz/125 g) coarsely grated fontina cheese
Makes 8 servings
Preheat the oven to 375°F (190°C). Prepare the tart shells and prebake as directed. Leave the tart shells on the rimmed baking sheet.
Heat the olive oil in a frying pan over medium heat. Add the onion with a pinch each of salt and pepper and cook, stirring occasionally, until the onion just begins to soften, 2–3 minutes. Add the squash and sage and continue cooking until the onion is soft and translucent and the squash is softened, about 4 minutes more.
Add the chard, sugar, and a pinch each of salt and pepper. Stir well, cover the pan, and cook until the leaves begin to wilt, 2–3 minutes. Remove the cover and stir the chard well, continuing to cook until the leaves are wilted and most of the moisture has evaporated, about 2 minutes more. Transfer the mixture to a bowl and let cool for about 10 minutes. Add the fontina, and stir to combine.
Divide the squash mixture evenly among the tart shells, filling them just below the top. Bake until the cheese is just melted, 4–6 minutes.
Remove the baking sheet from the oven and increase the oven temperature to 425°F (220°C). Crack an egg on top of each tart, sprinkle with a pinch each of salt and pepper, and return to the oven. Bake until the egg whites are just opaque and the yolk is still a bit runny, about 5 minutes. Remove from the oven, unmold the tarts and transfer to plates, and serve.