This is my second attempt at making hollandaise. I did it with a double boiler, and the recipe was 1 egg yolk, 4 tbsp of butter, a little water, lemon juice, salt, cayenne pepper, and black pepper. When I tried it, it was rich--almost repulsively buttery. As far as I can tell, the sauce looks right, and it definitely didn't break. My only thoughts are it needed more lemon juice to cut the butter or more air in the emulsion. I might have also cooked it a bit too cool as it started to solidify within 5 minutes of plating.
Many recipes call for different ratios of egg yolk to butter. Egg yolk size can vary substantially. Your recipe is definitely at the low egg/high butter end of the spectrum.
Considering it came out looking great, add another egg yolk next time, and another the time after that.
I like 3 yolks with half a stick of butter, made with USDA AA large eggs, cooked sous vide (no double boiler).
When I make hollandaise sauce, I use the ratio of 2 tbsp butter per 1 egg yolk. I find that it gives the sauce a custard-like texture without being overly buttery. That being said, if you prefer a richer, thicker sauce, you could try 3 tbsp butter per 1 egg yolk, and continue lowering the butter-to-yolk ratio until you find a thickness you are happy with. Or, as the other answer said, you could try adding more egg yolks, but keep in mind this will make a larger amount of sauce.