For a single portion, just place a portion on a plate and microwave until warmed through. 2. For a larger portion, take your wonderful cold cake out of the fridge and place it onto a baking sheet or in a baking dish (depending on which fits the uneaten portion the best). 3. Bake in the oven at 350 degrees F for about 10-15 minutes or until heated through.  4. The center should be wet while the cake is fully warmed. 5. The cake won’t be exactly as runny as it was when fresh because over time the moisture is absorbed into the cake and it melts less during reheating. The tastes should still be incredible though!