Mix yeast, milk, and sugar to bloom, let stand 10 minutes.
With dough hook or mighty arms, beat in eggs, then flour ½ cup at a time, then butter a few cubes at a time. Beat for 8 minutes (or knead if going by hand), or until windowpane test passes.
Cover and let rise 40 to 60 minutes, or refrigerate and slow-rise overnight.
Turn out onto a clean surface and roll out to ½" thick. Cut into circles. Place on floured baking sheet.
Cover and let rise 30–45 minutes.
Fry in 1½" oil for about 1–2 minutes, until golden brown on the bottom. Flip and fry the other side.
To fill, poke with a chopstick and swipe it back and forth until a pocket forms, then use pastry bag to fill.
Jam/jelly: Regular table jam/jelly.
Boston creme: Pastry cream filling. Topping: 1/3c. whole cream heated to simmer and then dissolve 4oz chocolate (chips or chopped up) in it. Allow to cools somewhat, then dip the tops in it.
Maple glaze: 1/3 c. maple syrup (Robust Dark Amber, formerly Grade B, is best) with 2 Tsp. butter, heat on medium until melted, whisk in 1c. confectioner's sugar. Dip, allow to cool, dip again. If the glaze tightens up, heat it again.