Turn up to medium speed, then cut butter into flour mixture until evenly distributed. (My mother always said it should look like cornmeal).

Change the whisk attachment for the dough hook. Using medium speed again, slowly add the buttermilk until the dough comes together. You might have to stop the mixer a couple of times to scrape flour from the sides and bottom of the bowl. If the dough is still sticky, add a tablespoon or more of flour. If it's too dry, add a little more milk.

Take the dough out of the bowl and off the hook and turn it onto a lightly floured surface. It shouldn't be too sticky. With your fingers or a rolling pin, spread the dough out until it is 3/4 inch to an inch in thickness.  This is important if you want to be able to split the biscuits before eating. Use a 2 1/2 inch cookie or biscuit cutter or a glass to cut out the biscuits. Gently reform the dough, roll out and cut the remaining biscuits.