Pour warm milk into a bowl; mash in yeast cakes. Mix in butter, eggs, sugar, cardamom, salt, and 3 1/2 cups flour. Use a wooden spoon to mix dough together. If very sticky, add remaining 1/2 cup flour. Cover the bowl; let dough rise for 30 minutes.

Beat together butter and sugar in a medium bowl until filling is creamy. Stir in cinnamon until combined. Set aside.

Transfer dough to a floured surface; knead until firm, about 3 minutes. Divide dough in half; roll each half into a 1/2-inch thick rectangle. Spread each rectangle with 1/2 of the filling.

Stack dough rectangles on top each other, filling-side up. Roll dough into a log starting with edge closest to you. Cut log into 1-inch-thick slices.

Preheat the oven to 425 degrees F (220 degrees C). Line a baking sheet with parchment paper. Alternatively, grease a baking dish or 2 cake pans.

Place rolls on the prepared baking sheet about 3 inches apart. If baking pull-apart rolls, arrange in the prepared baking dish or cake pans about 1 inch apart. Let rolls rest at room temperature for 20 minutes.