1Whisk together brown sugar, eggs, vanilla bean paste, and cardamom in a large bowl until smooth.
2Add sweet potato puree and sour cream to the wet mixture and whisk until fully combined.
3Pour in all-purpose flour, baking powder, baking soda, cinnamon, nutmeg, and salt into the wet ingredients.
4Mix until a dough forms.
5Cover the bowl with plastic wrap and chill the dough for at least 30 minutes.
6Prepare the glaze by whisking powdered sugar, honey, brown butter, vanilla bean paste, cardamom, milk, and flaky sea salt in a separate bowl until smooth.
7Flour a clean surface and transfer the chilled dough onto it.
8Lightly flour the top of the dough and roll it out to about 1/2 inch thick.
9Cut out donut shapes using a donut cutter and the donut holes using a small donut hole cutter.
10Carefully transfer the cut donuts and holes onto a baking sheet lined with parchment paper.
11Heat frying oil in a large pan over medium heat to 350°F (175°C).
12Carefully place a few donuts and donut holes into the hot oil and fry for 1-2 minutes per side until golden brown.
13Remove the fried donuts from the oil using a slotted spoon and place them on a wire rack to cool slightly.
14Dip each warm donut into the prepared glaze, ensuring it's fully coated.