Blender Hollandaise sauce is easy and always works for me. I have a recipe in an old McCalls cookbook.
But if you want a real cheat, add fresh lemon juice to good quality mayo, a bit of zest too. Basically Hollandaise is a warm lemon mayo.
If doing the blender version, add barely a pinch of cayenne or hot paprika to the blender. It does not make the sauce spicy, but does enhance the flavour.