Make Dough:

Bring milk and cream to barely a simmer in small saucepan over medium heat. Cool to 105?-115F.

Stir together warm water and yeast in mixer bowl and let stand until foamy, about 5 minutes. Add warm water mixture, sugar, flour, and salt to yeast mixture and mix at low speed, scraping down side of bowl as necessary, until flour is incorporated. Increase speed to medium and beat 6 minutes. Dough will be sticky.

Transfer dough to a lightly oiled large bowl and turn to coat with oil. Cover with a kitchen towel (not terry cloth) and let rise in a draft-free place at warm room temperature until doubled, about 2 hours.

For Hamburger Buns:

Butter 2 large baking sheets. Punch down dough, then divide dough into 16 equal pieces (about 3 oz each). Form dough pieces into a round, somewhat flat shape, and put about 3 inches apart on prepared baking sheets. Loosely cover with oiled plastic wrap and let rise in draft-free place at warm room temperature intil they hold a finger mark when gently pressed, 1 1/2 to 2 hours.

Preheat oven to 375? F., with racks in upper and lower thirds of oven. Brush buns with the egg mixture and sprinkle with sesame seeds. Bake, switching position of sheets on racks halfway through cooking time, until tops are golden and buns sound hollow when tapped, 20-25 minutes. Transfer to racks to cool completely.

For Hot Dog Buns:

Butter 2 13x9 inch baking pans. Punch down dough, then divide into 16 equal pieces (about 3 oz each). Roll each piece of dough into a 6-inch long log on a lightly floured surface. Space 8 logs evenly in each prepared pan so there are 2 columns of logs that run parallel to long sides of pans. Loosely cover buns with oiled plastic wrap and let rise in a draft-free place at warm room temperature until buns just start to touch, 1 1/2 to 2 hours.

Preheat oven to 375F., with racks in upper and lower thirds of oven. Bake buns, switching position of pans halfway through, until tops are golden and buns sound hollow when tapped, 20-25 minutes. Cool in pans 10 minutes, then transfer to racks to cool completely. Before using buns pull apart and cut lengthwise down center of each (but not all the way through).