You just will not get the marzipan to ooze into the cake batter if it starts off fridge-cold. In dire straits, I have cubed it and given it a quick whirl in the microwave. And if you wanted to replace the vanilla extract with the zest of an orange, I wouldn't mind in the slightest.
Marzipan cake with pears in white wine and vanilla - having an almond allergy I would never follow this recipe but ... doesn't it look amazing! I'm sure I can work with the idea to make an impressive pear cake/dessert