In the stand mixer bowl add yeast, sugar and warm milk. Mix and wait for a foamy top. This ensures your yeast is fresh.
Add sourdough discard and butter to bowl and mix with bread hook on low. May also add honey if you want it sweeter.
In separate bowl combine flour and salt.
Add the flour mixture to mixer bowl and mix on low until dough forms.
Increase speed to medium and let the mixer knead the dough for about 5 minutes
The dough should pull away from the bowl turning into a ball and you should be able to poke the dough without it sticking to your finger. If sticky you may need to add a little flour and mix it again.
Next transfer dough to a greased bowl and cover with plastic wrap and let it rise for about 2 hours. The dough should double in size.
Remove proofed dough from bowl onto a clean countertop. Stretch it out several times into the shape of a rectangle, the width of your pan. Roll the dough tightly, pinching the seams together and place seam down in a lightly greased loaf pan.
Cover with plastic and let rise again for about 1 hour or until the dough is about 1 inch above the rim of the pan.
Preheat oven to 350℉.
Bake for 35 minutes until the top is golden brown or the internal temperature reaches 190℉.
Remove from oven and remove bread from pan. Brush top with butter and cool on wire rack.