Make this classic bakery treat from the comfort of your own kitchen. These puffy doughnuts are filled with your favorite raspberry jam and rolled in granulated sugar.
Place yeast and 3/4 cup plus 3 tablespoons buttermilk in the bowl of an electric mixer. Add powdered milk and 2 cups flour. Let stand 3 minutes. Using paddle attachment, mix on low speed 30 seconds. Increase speed to medium high; mix until dough is smooth and comes together, 2 to 3 minutes; the dough will be very sticky.
Sift an even layer of flour onto a clean work surface. Turn out dough, and gather into a ball. Clean and lightly oil mixer bowl. Transfer dough to oiled bowl; cover with plastic. Set aside in a warm place to rise until doubled in size, about 1 1/2 hours.
Add remaining 5 tablespoons buttermilk, remaining 2 1/4 cups plus 2 tablespoons flour, sugar, salt, butter, nutmeg, cinnamon, and 8 egg yolks to yeast mixture. Mix on low speed until just combined, about 2 minutes. Increase speed to medium; beat until fully incorporated, about 3 minutes. Add 5 more egg yolks; mix on low speed 30 seconds. Increase speed to high, and beat 1 minute; dough will be very sticky.
Lightly oil a large bowl. Sift a heavy coat of flour onto a clean work surface. Turn out dough. Sift another heavy layer of flour over dough. Gather dough into a smooth ball. Place in oiled bowl, cover, and set aside until doubled in size again, about 30 minutes.
Heat oil in a low-sided six-quart saucepan over medium-high heat until a deep-frying thermometer registers 375 degrees. Lightly flour two baking pans, and line another one with paper towels; set pans aside.
In a small bowl, whisk remaining 2 egg yolks; cover with plastic. Place jam in a bowl; whisk until smooth. Set both aside.
Turn out dough onto a heavily floured work surface. Divide the dough into two equal pieces. Working quickly, roll one piece of dough, stretching as you roll, into a 12- by-14-inch rectangle, about 1/4 inch thick. Using the dull side of a 2 1/4-inch round doughnut cutter, score 15 circles, spaced 1/4 inch apart. Using a pastry brush, brush each marked circle with beaten egg. Place 1 teaspoon jam in middle of each circle.
Roll out the second piece of dough as the first. Carefully roll dough around the rolling pin, and, lining up edges, unroll it directly over first. Using dull side of a 1 1/2-inch round doughnut cutter, gently press around each mound, sealing layers, being careful not to cut through dough. Using sharp side of a 2 1/4- inch-round cutter, cut out doughnuts, being careful to keep jelly centered and dipping cutter in flour before each cut. Transfer doughnuts to a floured pan. Using a 1-inch round cutter, cut holes out of remaining scraps; transfer holes to other floured pan. Allow doughnuts and holes to rest 15 minutes.
Working in batches of four, carefully transfer doughnuts to oil. Cook until golden on bottoms, about 2 minutes. Using a slotted spoon, turn doughnuts over, and cook until golden all over, 2 minutes more. Transfer doughnuts to the lined baking pan. Repeat with remaining doughnuts and holes.
When doughnuts and holes have cooled, roll in sugar, and serve.