1. Preheat the oven to 400°F (200°C).

2. Roll out the dough to your desired thickness and use a cookie cutter or the rim of a glass to create circles that are slightly larger than your portion molds. Carefully line the molds with the dough, pressing it into the corners.

3. Peel the onion and chop it into small pieces, then sauté it in a generous amount of butter until softened and translucent.

4. Dice the potatoes and anchovies, then mix them with the cooked onion in a bowl until well combined.

5. Divide the potato and onion mixture evenly among the dough-lined molds, filling them about three-quarters of the way full.

6. In a separate bowl, whisk together the eggs, heavy whipping cream, salt, and pepper until smooth.

7. Pour the egg mixture over the filling in each mold, making sure not to overflow the edges.

8. Sprinkle a pinch of breadcrumbs over the top of each mold, followed by a small pat of butter.

9. Place the molds in the middle of the oven and bake for 20 minutes, or until the edges are golden brown and the centers are set.

10. Remove from the oven and garnish with chopped fresh dill and a squeeze of lemon juice, if desired.