Cut 2 1/2 sticks unsalted butter into cubes. In a saucepan, melt the butter over low heat. In a blender, pulse 2 large egg yolks and 1 to 2 tbsp. lemon juice (depending on how lemony you like it) until smooth. With the blender running, slowly pour in the warm melted butter, leaving the white milk solids in the pan. Blend until silky, about 2 minutes. Season with salt, pepper, and lemon juice to taste. Spoon over poached eggs set atop crisped slices of Canadian bacon on toasted English muffins.