Welcome to Amy Gillespie via Bloglovin.
I call these muffins simply because they are baked in muffin cases in a muffin pan. The recipe though is a simple Victoria Sandwich cake, using 4 eggs as the weight, then weighing all other ingredients to that weight (except the pineapple).
I did this as an all in one mix, which is how I do all my cakes. A small tin of pineapple chunks was drained (save the juice), patted dry then diced but saving 4 chunks for slicing and putting on the top before baking.
Here they are ready to go in the oven:
One slight problem with this bake was that I didn't have a block of St--k margarine which I always use. As our shop was done in Lidl, we opted to buy their version, Vita D'Or baking fat. Looked similar but the main difference (and the reason I shan't be using it again) was that when I removed the buns from the tin, the bases of each one were swimming in liquid fat. Never had that before and don't want it again. You can also see how dark brown the bases are inside the cases - don't get that very often either!
Anyway, they tasted great.