Position a rack in the upper third of the oven and preheat to 450 degrees F. Whisk or sift together the flour, baking powder and salt in a mixing bowl. Cut in the bacon fat with a pastry blender, fork, or two knives until it resembles damp, coarse meal with occasional lumps no larger than very small peas.
Make a well in the center and pour in half a cup of milk. Mix with as few strokes as possible until the dough clumps together and pulls away from the sides of the bowl, adding more milk (if needed) by spoonfuls until it is no longer crumbly.
Turn out onto a lightly floured work surface and pat out 1/2-inch thick. Fold it in half and pat out 1/2-inch thick, fold again, and repeat twice more.
Lightly flour the surface once more and roll or pat the dough out about 1/4-inch thick. Using 1 1/2-inch-diameter biscuit cutter dipped in flour before each cut, cut the dough straight down, without twisting the cutter, into 12 biscuits, transferring them to an ungreased baking sheet spaced about half an inch apart.
The scraps can be reworked with care: gather into a lump and lightly fold and pat flat about three times or until they just hold together, then pat flat and cut as above. Bake the biscuits until golden brown, about 8 to 10 minutes, and serve piping hot.
Notes: One slice of thick-cut bacon should yield about a tablespoon of rendered fat. Store the drippings for up to 4 weeks, well sealed, in the refrigerator, or for up to 3 months in the freezer.