Adjust the oven rack to the lower-middle position. Preheat the oven to 375°F.

Place bacon on a foil lined sheet pan. Roast in the oven until crispy, about 15 to 20 minutes. Drain on paper towels, then chop once cooled.

In a medium-size bowl, whisk together the flour, baking powder, baking soda, salt, and sugar.

Cut 1 cup of cold butter into 1⁄8-inch thick pieces. Add a few butter slices at a time into the flour mixture and toss to coat.

Press each slice of butter between the floured thumb and pointer finger, pressing and breaking the butter off into flat, nickel-sized pieces.

Repeat the process with the remaining pieces of butter, then toss to combine. Freeze the mixture in the bowl until chilled,15 minutes.

Add the chopped cooked bacon, cheddar cheese, and green onions to the flour mixture. Stir the ingredients to combine.

Gradually add 1 ¼ cup buttermilk into the chilled flour mixture, stirring with a fork until incorporated.

Knead the biscuit mixture in the bowl a few times until a shaggy dough forms; it will look slightly dry.

Lightly dust a working surface with the flour. Turn the mixture onto the floured surface and shape and press with hands until combined into a 1-inch thick square, about 8 x 8 inches.

Cut the dough into 4 even-shaped squares and stack as evenly as possible on top of each other.

Lightly flour a rolling pin and roll the dough out into a 1-inch thick square, about 8 x 8 inches.

Leave about a 1⁄4-inch border along the edges when cutting the biscuits to give even layers. Using a 2 3/4 -inch floured biscuit cutter, press the cutter straight down into the dough, without turning.

Transfer to a parchment paper–lined baking sheet and repeat with the remaining dough.

Refrigerate the biscuits for 30 minutes before baking.

Adjust the oven rack to the lower-middle position and preheat the oven to 450°F.

Transfer the biscuits to a new parchment paper–lined sheet pan. Make sure that the biscuits are at least 1 inch apart on the sheet pan.

Melt 2 tablespoons butter, brush on top of each biscuit and sprinkle with salt.

Bake the biscuits until golden brown, 12 to 15 minutes. Cool for 5 to 10 minutes before serving.