Fastnachts

Mix 1 cup sugar and cinnamon in a bowl; set aside. Combine milk, mashed potatoes, 1⁄2 cup sugar, and the shortening; beat, using a hand mixer, until combined. Combine water, remaining sugar, and the yeast in a stand mixer fitted with a paddle attachment; let sit until foamy, about 10 minutes. Add reserved potato mixer and mix until combined. With the motor running, slowly add 2 cups flour; beat until dough is smooth. Cover loosely with plastic wrap; set in a warm place for 30 minutes. Add orange zest, salt, mace, and egg; with the motor running, slowly add remaining flour. Transfer dough to a lightly floured work surface and knead 5 minutes, or until smooth. Transfer dough to a lightly greased bowl and cover loosely with plastic wrap; set in a warm place until doubled in size, 1 1⁄2 hours.

Turn dough onto lightly floured surface; roll dough into a 14" round about 1⁄2" thick. Using floured 3" ring cutters, cut out donuts; gather and reuse scraps. Place on greased parchment paper–lined baking sheets, at least 3" apart, and cover loosely with plastic wrap; set in a warm place until doubled in size, about 45 minutes.

Heat 2" oil in a 6-qt. saucepan until a deep-fry thermometer reads 325°. Using scissors cut the donuts out of the parchment paper, leaving about 1" of paper around the sides of each donut (the paper makes it easier to transfer them to frying oil). Working in batches, place donuts in oil, paper side up, using tongs to peel off and discard paper. Cook, flipping once until puffed and golden, about 3–4 minutes. Using a slotted spoon, transfer to a baking sheet with a wire rack; let cool slightly. Toss in sugar mixture.