Preheat oven to 450 degrees. In a skillet, cook bacon to desired crispness. Drain and chop.In a mixing bowl, combine flour, baking powder, baking soda, and 1 tablespoon cajun seasoning. Cut in shortening. Add bacon and blue cheese, then mix in buttermilk until a sticky dough forms.Turn dough out onto a floured surface and knead until it comes together. Roll out to ½-inch thick and, using a 2½-inch cutter, punch out biscuits. Bake at 450 degrees for 12 to 15 minutes.Mix remaining cajun seasoning into softened butter and brush over biscuits when they’re fresh from the oven.