When I was a teenager and started to become passionate about cooking, one of the first cookbooks I bought was themed around melt-in-the-middle cakes (yes, quite a specific theme 😅). I don't remember the exact recipes, but the basic concept was always the same: you make frozen cubes of the melting heart in the freezer, place a cube in the center of each cake before baking, and the heart will melt in the oven while the cake cooks, so when you take it out of the oven, the middle is melting – easy!
And you can do this endlessly: a chocolate ganache, a caramel cream, raspberry puree… here it's vanilla custard :) I like chocolate in small doses, so softened with the custard, it's perfect for me!
Note: Be sure to start the custard several hours ahead or the day before (or even earlier) so that the cubes are frozen!
Since I didn't eat everything on the same day, I slightly undercooked my cakes and then froze them. Now, whenever I want a dessert, I just heat up a cake for a few minutes in the microwave or the oven and it becomes gooey again!