I started with this recipe from the New York Times, but made a much smaller batch of them with more lemon flavor.

Ingredients

For the dough:

• 3/4 teaspoon (2.3 grams) active dry yeast
• 1/3 cup buttermilk, warmed to 100 degrees (or, 1 tablespoon lemon juice + enough milk to reach 1/3 cup)
• 1 tablespoon (16 grams) sugar
• 2 2/3 tablespoons (38 grams) unsalted butter
• 1/2 heaping tablespoon finely grated lemon zest
• 1/3 teaspoon kosher salt
• 1/4 teaspoon cardamom
• 1 egg, lightly beaten
• 1 1/3 cup (171 grams) all-purpose flour, plus more for work surface

For the filling:

• scant 1/3 cup sugar
• 1/2 heaping tablespoon lemon zest
• 1/4 teaspoon cardamom
• pinch of kosher salt
• 2 tablespoons unsalted butter, very soft

Directions

Combine the yeast, buttermilk, and a sprinkle of sugar. Let sit until foamy, about 5 minutes

Add the butter, remaining sugar, lemon zest, salt, and cardamom to the bowl of a stand mixer fitted with the paddle attachment. Mix on low to combine. Add the eggs and buttermilk mixture. Mix on low to combine.

With the mixer on low speed, add flour and stir until all of the flour is moistened. Switch to the dough hook, and mix for 5 more minutes. The dough will be soft and billowy. It will stick to the bottom of the bowl. Add more flour if the dough seems very very soft.

Transfer the dough to a fresh bowl that has been lightly oiled. Turn the dough to coat it in oil. Cover the bowl with a kitchen towel. Let the dough rise in a warm spot until doubled in size, about 1 hour. Alternately, refrigerate the dough before rising for up to 24 hours.

While the dough is rising, make the filling. Rub the lemon zest into the sugar until you smell the lemon bloom. Add the cardamom and pinch of salt. Stir to combine.

Line an 8-by-8-inch baking pan with parchment paper. Butter the parchment paper and the pan. Gently deflate the dough by folding it over on itself a few times in the bowl. Turn the dough out on a floured surface. Pat or roll it out into a 12-by-8-inch rectangle that is about 1/4-inch thick. Spread the soft butter over the rectangle, then sprinkle the lemon sugar evenly over the top. Roll the dough into a tight log. Use a serrated knife to cut the log into 8 even pieces.

Place the rolls into the prepared pan. Cover with a kitchen towel. Let the rolls rise in a warm spot until doubled in size, about 1 hour (possibly more if you did a cold rise for the previous one). Alternately, refrigerate the rolls before the second rise for up to 24 hours. Let the rolls rise at room temperature until doubled in size.

Heat the oven to 350 degrees. Bake for 25-30 minutes or until the rolls are golden and baked through.