In a large bowl or stand mixer, stir together the yeast, 1 tablespoon sugar, and ¼ cup warm milk. Let sit for 5 minutes until the yeast is foamy.
2 ½ teaspoons active dry yeast, ⅓ cup granulated sugar, ¾ cup warm milk
In the meantime, mix together the remaining ⅓ cup sugar, ½ cup warm milk, melted butter, and salt. Add that mixture to the yeast once proofed along with the egg, Meyer lemon zest, and cardamom. Stir until thoroughly combined.
2 tablespoons melted butter, ¾ teaspoon kosher salt, 1 large egg, 1 teaspoon Meyer lemon zest, ½ teaspoon ground cardamom
Add the flour. If using a stand mixer, attach the dough hook and mix on low. If mixing by hand, use a sturdy wooden spoon or spatula. Mix until the dough starts to pull away from the bowl, about 2 minutes. If it is very sticky, add 1 tablespoon of flour at a time until it comes together. Avoid adding more than ½ cup extra.
2 ½ cups flour
Turn the mixer to medium and knead for 5 minutes, or knead by hand on a lightly floured surface until smooth and elastic, about 8 minutes.
Place the dough into a lightly oiled bowl, cover, and let rise in a warm, draft free spot until doubled, about 1 to 2 hours.
When doubled, turn the dough onto a lightly floured surface and roll it to ½ inch thick. Use a donut cutter to cut out as many as possible, then reroll the scraps.
Place donuts on parchment lined baking sheets. Cover and let rise again until doubled.
Preheat the oven to 400°F. Brush the tops with melted butter, then bake for exactly 7 minutes. Do not let them brown.
Allow donuts to cool completely. Make the glaze by combining the Meyer lemon zest, juice, milk, cardamom, salt, and melted butter. Add powdered sugar and whisk until smooth.
1 teaspoon Meyer lemon zest, 2 tablespoons Meyer lemon juice, 2 tablespoons whole milk, ¼ teaspoon cardamom, pinch of salt, 1 tablespoon melted butter, 2 cups powdered sugar
Dip donuts into the glaze on all sides except the bottom. Transfer to a rack and let set for 20 minutes.
Optional: Return the glazed donuts to the oven at 400°F for about 2 minutes to help the glaze soak in. Cool before serving.