Preheat oven to 425°F. Line a large sheet pan with parchment paper or foil and set aside.
In a mixing bowl, whisk together flour, baking powder, sugar, baking soda, and salt.
Toss cold butter and cream cheese cubes into the dry ingredients and, using a pastry cutter or your fingers, mix in the cold butter until you have a mixture of flat pieces and crumbly, pea sized bits of butter mixed into the flour. Add 3 tablsespoon of everything bagel seasoning and mix in.
Make a well in the center of the mixture and add the cold buttermilk. Gently mix the buttermilk and the dry ingredients together until you have a fairly uniform, loose dough. The flour won't look all mixed in and that's okay. It will come together.
Dump the shaggy dough out onto a lightly floured surface. Using your hands, gently bring it everything together into a rough square.
With a bench scraper or knife, cut into four smaller squares. Stack the pieces of biscuit dough on top of each other. Smush it all down into a square again. Repeat this cutting and stacking procedure 2 more times.
Pat the dough into a rectangle at least ½ inch thick. Using your favorite biscuit cutter or cookie cutter, cut out your biscuits. Gather your scraps as you go and gently re-form them together and cut as many biscuits as you can. Place sheet pan in the freezer for 10-15 minutes while you preheat your oven.
Remove biscuits from the freezer. Brush the tops of the biscuits lightly with an egg wash made of one egg whisked with one tablspoon of water. Sprinkle the top of each biscuit with more everything bagel seasoning. Bake in a 425°F oven for 20 to 25 minutes, or until golden brown.