Dissolve the yeast in the warm water.

Add milk, sugar, salt, eggs, butter, hibiscus flavor, and 2 cups flour.

Beat on low for 30 seconds with the paddle attachment, scraping the bowl if needed.

Beat on medium speed for 2 minutes, scraping the bowl occasionally.

Switch to the dough hook attachment and knead in the remaining 3 cups of flour until smooth.

Cover the bowl with a dishcloth and let the dough rise until it has doubled in size, about an hour.

Turn dough onto a floured surface and roll dough 1/2-inch thick.

Cut with floured doughnut heart. Use a smaller heart cutter to create the heart-shaped insert. Transfer to a parchment-lined baking sheet or tray.

Cover and let rise again until doubled in size, 30-40 minutes.

Place a layer of paper towels next to the stove.

Transfer to the paper towels.

Heat butter until melted over medium-low heat and remove from the stove.

Whisk in the powdered sugar, buttermilk, and hibiscus flavor until smooth.

Dip the doughnuts into the glaze and set them on cooling racks over parchment or foil-lined baking sheets.

Sprinkle with the dried hibiscus.

Let the glaze harden completely before serving.