You need to set up a double boiler. Make sure to use clarified butter or it will break. Only use the yolks too. As soon as the eggs are tempered over the boiler, slowly drizzle the butter while whisking. You can turn off the heat right as you start drizzling too. Powdered mix is nowhere near the same quality.

Start with a white wine / tarragon reduction and then add yolks and follow the same procedure for a killier bearnaise sauce.

I should add: once the hollandaise is finished, add salt to taste and a touch of lemon juice.