Preheat Oven and Prepare the Tin:

Preheat your oven to 350°F (175°C). Line a muffin tin with muffin liners or grease the cups lightly.

Prepare the Raspberry Filling:

In a small saucepan, heat the raspberries and sugar over medium heat until the raspberries break down and become syrupy (about 5–7 minutes). If using jam, skip this step and simply spoon it directly into the cupcakes. Let the raspberry mixture cool.

Melt the Chocolate and Butter:

In a microwave-safe bowl, melt the chocolate chips and butter together in 30-second intervals, stirring between each, until smooth and fully melted. Let it cool slightly.

Make the Cupcake Batter:

In a separate bowl, beat the eggs and sugar together until fluffy. Add the melted chocolate mixture, flour, vanilla extract, and salt, and mix until just combined. The batter will be thick.

Assemble the Cupcakes:

Spoon a small amount of cupcake batter into the bottom of each muffin liner (about 1 tablespoon).

Add a teaspoon of the cooled raspberry filling in the center of each cupcake. Top with more cupcake batter to fully cover the raspberry filling.

Bake:

Bake the cupcakes for 12–15 minutes, or until the edges are set but the center is still slightly soft. Be careful not to overbake, as the lava effect comes from the gooey center.

Cool and Serve:

Let the cupcakes cool for a few minutes before carefully removing them from the tin. Dust with powdered sugar and garnish with fresh raspberries if desired. Serve warm to enjoy the molten raspberry chocolate center.