• In the bowl of a stand mixer fitted with the dough hook attachment, add warm milk, melted butter, sugar, salt, vanilla and sourdough starter.  Mix on low speed until combined.
• While the mixer is running, add flour one cup at a time to the wet ingredients.
• Turn mixer onto medium speed and allow it to mix for at least 10 minutes.  You want the gluten in the dough to be developed enough that you can pull the dough up and get it thin enough to see through it without it tearing.  This is sometimes called windowpane test.  (See video below)
• If you want to make cream filled donuts, it’s a good idea to make the cream filling while the donuts are mixing. This way it can be well chilled before morning when you will fry the donuts.
• On a lightly floured surface, roll dough out until it is ½” thick.
• Using a large heart-shaped cookie cutter, cut out the donuts.  Then use a small heart shaped cookie cutter to cut out the center of the donut.  If you want to make any jam or cream filled donuts, you’ll want to cut them out without any holes in them.
• Place the donuts on two parchment lined baking sheets.  You will have to re-roll your dough at least once to use up all your dough.
• Cover the donuts with the other two cookie sheets to help seal in the moisture.  This will allow the donuts to rise and proof overnight, without them drying out.
• Allow to rise at room temperature overnight or 8-12 hours.

Frying The Donuts

• In the morning, heat 3-4” of beef tallow or oil in a 6 quart dutch oven or similar sized heavy bottom pan over medium heat.  Heat until the oil is close to 375 degrees.  Keep in mind that your oil will cool off once you add the first round of donuts, so it’s best if the oil is on the hotter side.
• Carefully drop 3-4 donuts in the hot tallow or oil.  There should be enough oil in the pot that the donuts do not reach the bottom.  These are deep fat fried donuts, so the oil has to be deep enough that they will float.  Let them fry on one side just until that side starts to turn a golden brown.  This usually takes about a minute.
• Using metal tongs or a slotted spoon, flip the donuts over and fry on the other side just until brown.  Don’t fry them too long or they will get extra crispy and not be quite as good.
• Remove the donuts from the tallow and place on a wire rack that is on a baking sheet.  Allow the oil to drip off while frying the rest of the donuts.
• Check the oil temperature between each batch of donuts making sure it doesn’t drop below 350 degrees and go above 375 degrees.  Adjust heat as necessary.
• Fry until all the donuts are done (see video).  The excess oil can be saved for frying other things or cooking.

Topping The Heart Donuts

• Mix up strawberry glaze or other topping. 
• Fill donuts with filling if desired, or cover with glaze or toppings.  There are SO many ways to top these, so use your imagination.
• Enjoy with some coffee or tea and a side of fresh fruit for a delicious and comforting Valentine’s Day breakfast.
• Store leftovers in an airtight container on the counter for a couple of days.  Sourdough donuts can also be frozen before adding the toppings for up to three months.