Here’s another recommended recipe we found from Cookpad Spain.
Reference Link:
Low-Calorie Custard Prepared in the Microwave:

50 grams [A] Sugar

1 tbsp [A] Cake flour

2 tbsp [A] Cornstarch

50 ml + 150 ml Milk

1 Egg yolk

1/2 tsp each [B] Rum, brandy

1 dash [B] Vanilla extract

Place the [A] ingredients into a heat-resistant bowl and mix together with a whisk until fluffy. Sift together if possible.

Add 50 ml of the milk and mix. Then add the egg yolk and mix before adding the remaining 150 ml of milk and mixing again. Strain once.

Microwave for 2 minutes. Remove and mix again with the whisk. Microwave again for 1 minute and mix again.

Add and mix the B ingredients to finish. Cover the outer surface of the cream with cling film and cool.

I made cream puffs with this. The cream I used here was prepared on the stiff side. Please adjust the stiffness according to what you’re making.