Caramelized Onion and Olive Tart

Instructions

1. Caramelize the onions
   Heat olive oil and butter in a large skillet over medium-low heat. Add the sliced onions with a pinch of salt and cook, stirring occasionally, for about 45-50 minutes until deeply golden and caramelized. Add the sugar halfway through to help with caramelization. In the last 5 minutes, add the sliced garlic and thyme leaves.
2. Prepare the pastry
   Preheat oven to 200°C (400°F). Roll out the puff pastry on a floured surface to fit a 9-inch tart pan or baking sheet. If using a tart pan, gently press the pastry into the pan, trimming any excess. If using a baking sheet, fold over the edges to create a small border. Prick the base all over with a fork to prevent it from puffing up too much.
3. Assemble the tart
   Spread the caramelized onion mixture evenly over the pastry base, leaving a small border if on a baking sheet. Arrange the olives evenly across the top. If using anchovies, scatter them over the tart. Brush the exposed pastry edges with beaten egg.
4. Bake the tart
   Bake in the preheated oven for 25-30 minutes, until the pastry is golden brown and crisp. If the edges are browning too quickly, cover them loosely with foil.
5. Finish and serve
   Remove the tart from the oven and let it cool for 5-10 minutes. Drizzle with a little extra olive oil, sprinkle with fresh thyme leaves, and add freshly ground black pepper. Slice into portions and serve warm or at room temperature.