There are three steps to making these delicious breakfast potatoes! If using a package of hollandaise sauce, follow the directions. If making homemade hollandaise sauce with a double boiler, add water and turn it up to high and bring water to a boil. While potatoes are browning, start making the hollandaise sauce. Check to see if the water in the double boiler is boiling. If using a heavy bottomed saucepan, place it on medium-low heat. Whichever method you use, melt the butter first. Add heavy cream. Then add egg yolks, lemon juice, hot sauce (if using) and mustard until blended. Continue to cook, whisking constantly, until mixture has thickened. Watch the pot doesn't get too hot. Don't let the sauce vigorously boil. You can take the pot on and off the double boiler, or element, as needed. When sauce thickens, remove it from the heat.