For the donut dough: In the bowl of a stand mixer fitted with the dough hook, place the flour, granulated sugar, baking powder and salt. Turn on to low speed to slightly mix all the dry ingredients. Add the milk, butter and egg, and mix until the dough is smooth, about 4 minutes.
Transfer the dough to a bowl, cover with plastic wrap and refrigerate 8 hours or up to overnight.
Turn the dough out onto a floured work surface, sprinkle more flour on top and roll out 1/2-inch thick. Using a donut cutter or drinking glass, cut out donuts and place on a tray to rest. Place the donuts back in the refrigerator until ready to cook.
Add the oil to large, deep saute pan or pot and heat it to 350 degrees F.
Using a slotted spoon, slowly drop 2 or 3 donuts into the hot oil, adjusting the heat to maintain the oil at 350 degrees F. Fry the donuts for 3 minutes, then flip and cook 2 minutes more. Drain on paper towels and fry the remaining donuts in the same manner. Set aside until ready to use.
For the glaze: Combine the confectioners' sugar and milk in a bowl and stir until smooth. (The mixture will thicken while it sits.) Reserve until needed.
For the burgers: Combine the chuck and brisket in a bowl. Grind the meat through the small die of a meat grinder into a bowl and mix until thoroughly combined. Wrap the bowl with plastic wrap and refrigerate for 4 hours to allow the meat to rest and thoroughly chill. Divide the meat into 8 portions and press into patties about 1/4-inch thick.
Preheat a saute pan over medium-high heat. Sprinkle the patties with salt and pepper and cook until cooked through, about 3 minutes per side. Top with Cheddar and allow to melt.
For the donut sliders: Split the donuts in half to open like sandwich buns. Brush the cut sides with mayonnaise. Place a burger on the bottom half of each donut and cover with the top half. Using a spoon, drizzle some glaze over the donuts, completely covering them. Enjoy them immediately.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy of The Original Dinerant, Portland, OR