In a bowl, whisk together the cake flour, baking powder, salt, nutmeg & baking soda. Set aside.

In a separate large bowl, whisk together both sugars & melted butter. Add the eggs/egg yolk & vanilla; whisk to combine. Whisk in the buttermilk.

Add dry ingredients to wet; fold until just combined (will be sticky). Cover & chill in the fridge for at least 30-60 mins.

Heavily flour a surface & your hands. Lay the dough out, sprinkle w/ more flour & gently roll into a large rectangle (18x3.5"; ½" thick), adding more flour as needed.

Flour a bench scraper & cut the dough all the way across lengthwise to divide it in half. Then, make 8-9 cuts widthwise, to get 16-18 bars.

Once cut, dip bench scraper or knife in flour again & VERY gently press it down the center of each bar lengthwise, without cutting in half, making a light indentation.

Fill a large pot or Dutch oven with oil, ~2" high. Heat on medium-high heat until it reaches 350F-370F.

Line a wire rack w/ a thick layer of paper towels.

Once hot, carefully transfer the donuts into the hot oil, 3-4 at a time. Start w/ the bottom side down, indentation side up. Fry the donuts for 1-2 mins on each side, until golden.

Using a slotted spoon, carefully transfer the donuts to the rack.

Whisk together the ingredients for the glaze; add more milk if too thick.

Dunk each bar & place a cooling rack until glaze sets.

Serve & enjoy!