Place the puff pastry side by side on the work surface and allow to defrost. Clean, wash and cut the spring onion into rings. Cut ham into short strips. Pour pineapple into a sieve and let it drain. Coarsely grate cheese
Whisk the egg yolk and milk together. Whip the puff pastry corners to the middle. Spread thinly with egg yolk. Spread ham, pineapple and spring onion rings on the pizzas. Sprinkle with cheese. Bake in the preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: see manufacturer) for approx. 10 minutes