Attach your dough hook to the stand mixer. Add melted butter and flour to the bowl and mix on low for a couple minutes. Then mix on medium for 5 minutes, until the dough pulls away from the sides. (Add a bit more flour if necessary). Remove dough from bowl, lightly oil the bowl with vegetable oil, then put dough back in bowl. Cover and set in a warm place to let dough rise, until it doubles in size. Approx 45 min-1 hour.