Combine all of the ingredients, and beat at high speed, using an electric mixer, for 2 minutes. To use your bread machine, put everything in the bucket, and let the dough go through its dough or manual cycle; skip to step 3 below if you're using a bread machine.
Place the dough in a lightly greased bowl or rising bucket, cover it, and let it rise for 60 to 90 minutes, until it's noticeably puffy.
Gently deflate the dough, and divide it into 6 pieces; each will be about 111g, a scant 4 ounces.
Shape the dough into balls, and place them in the wells of a lightly greased hamburger bun pan. If you don't have a bun pan, space them on a lightly greased or parchment-lined baking sheet.
Gently flatten the buns with your hand to fill the bottom of the pan's wells, or until they're about 3 1/2" to 4" wide.
Cover the buns, and let them rise for 60 to 90 minutes, until they're noticeably puffy. Towards the end of the rising time, preheat the oven to 350°F
Brush each bun with some of the melted butter.
Bake the buns for about 20 minutes, until they're a light, golden brown, and their interior temperature is at least 200°F, measured with an instant-read thermometer.
Remove the buns from the oven, transfer them to a rack, and brush with the remaining melted butter. Allow the buns to cool completely, then store airtight at room temperature.