Step #2 Coat four 12 c mini-muffin pans with vegetable oil cooking spray.
Step #3 In a saucepan, simmer the potatoes in water over med-heat/flame until tender, about 20 mins.
Step #4 Let cool slightly, then peel & coarsely mash the potatoes.
Step #5 Meanwhile, in a medium skillet, cook the sausage over high heat until browned, 8 mins, drain & coarsely crumble.
Step #6 In a medium saucepan, bring the water, butter, & salt to a boil.
Step #7 Remove from the heat & add the flour, stirring vigorously with a wooden spoon, until mixd.
Step #8 Set the pan over moderately high heat & cook the dough, stirring, until it comes away from the sides of the pan, 2-3 mins; remove this from heat.
Step #9 Using a handheld electric mixer, beat the dough at lowish speed for 1 min.
Step #10 Beat in the eggs one at a time at medium speed; beat in the Gruyere cheese, thyme, rosemary, Parmesan, & a pinch of pepper.
Step #11 Stir inthe mashed potatoes & sausage.
Step #12 Fill muffin c with the dough.
Step #13 Brush the tops with the egg wash & bake for 20 mins, or until puffed & golden.
Step #14 Let the puffs cool slightly, then serve hot.
Step #15 Can be put in the fridged over night; rewarm in a hot oven.