Cut sardines into 4 pieces, season with salt and pepper, let sit for 5 minutes, then pat dry.

Slice onion and mushrooms thinly, quarter cherry tomatoes, and slice black olives.

Cut frozen pastry sheets in half, lightly roll out, and place into greased ramekins lined with parchment paper.

Heat salad oil in a pan, sauté onion and mushrooms with a pinch of salt until softened, then remove.

Add salad oil to the pan and sear sardines on both sides until lightly browned.

In a bowl, whisk eggs, add salt, pepper, grated cheese, and milk, then mix in cooled sautéed vegetables, sardines, and olives.