Select the Bake function on the Ninja Foodi, set the temp for 375° and the time for 20 minutes. Combine flour, salt, baking powder and sugar in a metal mixing bowl or a chilled glass bowl.
Remove the butter from the fridge and cut into 1/4 inch slices into the bow with the flour. Use a pastry cutter or fork to combine the flour and butter until it has a very course texture.
Make a well in the middle of the flour/butter mixture and pour in the Greek yogurt and water mixture. Use a fork to gently combine the flour mixture and the liquid mixture. You should not have a dough yet. See video for details.
Dump mixture onto a floured surface and press down with your fingertips until you have a 4"x 4" piece of dough. Fold the top down to the bottom. Turn 90° and repeat x 5, gathering all the loose flour/butter as you go. Each time you press and rotate, make the square bigger, but don't go more than 8" x 8". Don't over work the dough,, see post for details.
When all the loose flour is incorporated, gently press dough down with your fingers until it is about 1" thick. Use a 2" biscuit cutter to cut out the biscuits. Press straight down, don't twist.
After you get as many biscuits as you can out of that dough, gently bring it back together and press it down again to 1" thick. You should get at least 8 biscuits. I got 10. Only 8 will fit in the Ninja Foodi, but see the post for details on freezing the other two.
Place cut biscuits in a circle around the Ninja Foodi basket, you should be able to get 6 or 7, depending on how big you cut them. Place one in the middle and put the basket into the inner pot.