Dissolve yeast and 1 tsp sugar in lukewarm water. Set aside to bloom for 5-7 minutes. There should be foamy with bubbles forming on top. If it doesn't, toss and start again.
In a medium-size mixing bowl, use a whisk to sift together flour, remaining 2 Tbsp sugar, baking powder, salt and baking soda.
Using a pastry cutter, 2 knives cut cold butter into the dry ingredients until it resembles cornmeal. Make a well in the center. (You may use 2 forks or even a hand mixer on low speed to cut the butter into the dry ingredients.)
To the well add buttermilk and yeast mixture. Use a fork to work the liquid into the flour until moistened.
Turn out onto a lightly floured surface and turn a few times, kneading just until the dough comes together. Form roughly into an 8 x 8 square that's ½-3/4 inch thick. (This allows room for dough to spread as it rises)
Use a sharp knife to cut into 9 or 12 equal pieces.
Pour half of the melted butter into a 9 x 9 inch baking pan. Swirl to coat bottom and halfway up sides. Arrange biscuits in pan, reshaping as needed to fit. Pour remaining melted butter on top. Cover with a damp cloth and allow to rise for 1 hour.
To bake: Preheat oven to 400°F. Bake butter biscuits for 15-20 minutes until puffed and golden.
Serve immediatly with butter, jam or sausage gravy.