Cinnamon-Cardamom Sufganiyot

Prepare the Sufganiyot:

1. Place warm water in bowl of a stand mixer fitted with a dough hook attachment. Sprinkle yeast over water; let stand until bubbly, about 5 minutes. Add warm milk, melted butter, sugar, salt, eggs, and 3 1/4 cups of the flour to yeast mixture; beat on low speed until ingredients are fully combined, about 1 minute. Increase mixer speed to medium; gradually add remaining 3 1/4 cups flour, and beat until dough pulls away from sides of bowl, about 8 minutes, adding 1 to 2 tablespoons additional flour as needed if dough is too wet. Transfer dough to a heavily floured work surface, and knead until smooth, about 4 minutes. Place dough in a large greased bowl; cover and let rise in a warm place, free from drafts, until doubled in bulk, about 1 hour.

Meanwhile, prepare the Cardamom Pastry Cream:

1. Whisk together sugar, flour, cornstarch, cardamom, and salt in a medium saucepan. Gradually whisk in eggs, cream, and vanilla until smooth. Heat over medium, whisking constantly, until mixture just begins to boil and is thickened, about 15 minutes. (Pastry cream should be stiff; when coating the back of a spoon, a line should hold its shape when drawing your finger through cream.) Remove from heat; whisk in butter until smooth. Spoon into a fine mesh strainer over a large, rimmed baking sheet; press mixture through strainer using a rubber spatula. Spread pastry cream in an even layer; cover with plastic wrap, ensuring plastic wrap touches top of pastry cream. Refrigerate until ready to use, at least 1 hour or up to 12 hours.

2. Punch down dough, and place on floured work surface; roll to a 3/4- to 1-inch thickness. Using a 4-inch round cookie cutter, cut out 12 rounds, rerolling dough scraps as needed. Place rounds 2 to 3 inches apart on 2 floured baking sheets; cover loosely using towels, and let rise in a warm place, free from drafts, until puffed, about 30 minutes.

3. Meanwhile, pour oil into a large Dutch oven to a depth of 1 1/2 inches; heat over medium-high until a deep-fry thermometer registers 350°F, adjusting heat as needed to maintain temperature. Whisk together cinnamon and 1/2 cup sugar in a large bowl; set aside. Working in batches of 3 or 4, gently place dough rounds into oil; cook, flipping once, until golden brown, 1 to 2 minutes per side. Using a slotted spoon or spatula, transfer Sufganiyots to a wire rack placed inside a large rimmed baking sheet. Let Sufganiyots cool for 1 minute; place in cinnamon-sugar mixture, tossing to coat. Return to wire rack, and let cool slightly, about 5 minutes.

4. Transfer cooled Cardamom Pastry Cream to a pastry bag or gallon-size  ziplock plastic bag fitted with an open star tip. Using a chopstick or a wooden skewer, gently press into side of each Sufganiyot, pressing three-fourths of the way inside. Gently wiggle chopstick to hollow out center and make space for piping tip. Insert tip of pastry bag into hole, and fill with about 3 tablespoons Cardamom Pastry Cream until it just begins to poke out the side. Transfer Sufganiyots to a platter, and serve.