Start proofing the yeast by combing it with the warm water and sugar in the bowl of a stand mixer. Allow to rest for about 15 minutes. Once the yeast blooms, it should have a small layer of froth on top.
Add the butter and 2 1/2 cups the flour to the bowl and mix for about 3 minutes on medium speed.
Add in ½ teaspoon salt and an additional 1 cup of flour. Lower the speed setting by one notch and let the dough knead for about 10 minutes before determining if it needs more flour. If the dough is starting to pull away from the edges, it should be the right consistency. If it is still leaving dough along the edges of the bowl, then 1/4 cup of flour at a time (or less) until the only area of the bowl that it's sticking to is the bottom.
Grease a large bowl, place the dough inside and create a loose tent with plastic wrap. Allow the dough to sit until almost double in size, about 40-45 minutes. Do not refrigerate.
Lightly grease the inside of an 8.5-inch x 4.5-inch loaf pan and set aside.
Turn the dough out onto a floured surface. Gently work the dough into a loaf shape before placing it into the prepared loaf pan. Loosely tent with plastic wrap until the dough has risen about 1 inch above the top of the pan - this will take another 40-45 minutes.
Preheat your oven 375 degrees F. Remove the plastic wrap from the dough and bake for 40 minutes. The top should be a golden brown and sound hollow if you lightly knock the top.
Remove the bread from the oven. Allow the loaf to sit for about 10 minutes in the pan before transferring it to a wire rack to cool. Let the bread to sit on the wire rack for at least 25-30 minutes before slicing.
Notes
Nutrition varies by the number of slices you cut from the loaf.