To make donuts: Boil potatoes, drain and mash, in a large mixing bowl and combine with sugar. Stir in orange zest. Reserve.
In a small pot, steep milk, cloves, nutmeg and fat over low heat. Strain and discard cloves.
Whisk eggs, then very slowly add steeped milk. Pour into potato mixture and stir to combine. Sift in dry ingredients and gently stir just to combine. Let rest for 1 hour.
Turn dough onto floured surface. Roll to 1/3-inch thickness, cut doughnuts and fry in 360F oil for 4 minutes, turning once. Using a slotted spoon, transfer to paper towel to drain. Drizzle with salted caramel glaze and serve.
To make glaze: In a small pan over medium heat, melt sugar, stirring constantly until golden brown. In a separate pan, bring cream to simmer. Slowly pour cream into sugar until combined. Whisk in salt. Cool to room temperature. Reserve.
Jeremy Specto, Wonder City Coffee & Donut Bar at The Brindle Room, New York City