Blend the coconut milk, milk, and pineapple in a blender until smooth.

In a saucepan, melt the butter over medium heat. Add the flour and mix well. Cook the flour slowly until it turns slightly golden.

Add the curry powder and cook for 1 minute.

Pour in the pineapple mixture, add salt and pepper, and stir well to dissolve the flour in the liquid. The sauce will thicken; let it cook slowly for about 15 minutes.

Add more milk if you want a thinner sauce. Stir frequently to prevent the flour from sticking to the bottom of the pan and burning.