Sprinkle the yeast over the lukewarm milk in a small bowl and stir briefly. Let it stand for 5 to 10 minutes until it looks frothy.

In a stand mixer bowl fitted with the dough hook, combine the flour, sugar, cardamom, and salt. Add the frothy yeast mixture, the egg, and the melted butter. Mix until the ingredients come together and a dough forms.

Knead the dough until it becomes smooth and elastic, about 8 to 10 minutes. If it feels crumbly, add a small splash of milk. Cover the bowl with a towel and let the dough rise for about 1 hour.

Heat the oven to 375°F and line a baking sheet with parchment. Divide the dough into 12 equal pieces and roll each piece into a ball. Place them about 2 inches apart on the sheet, then cover and let them puff for about 30 minutes.

Whisk the second egg with 1 tablespoon milk and brush the tops of the buns. Bake for about 15 minutes or until golden. Move the buns to a rack and let them cool completely.

Once the buns are cool, slice a 1/2-inch lid off each one and set the lids aside. Scoop out the centers, leaving a 1/2-inch wall and base.

Stir the scooped crumbs with 1/4 cup milk to soften them, then add the grated almond paste and work everything into a smooth paste. Spoon about 1 tablespoon of filling into each hollowed bun.

Whip the heavy cream with the powdered sugar until it reaches stiff peaks. Pipe the cream generously over the almond filling. Set the lids back on top and dust with powdered sugar, then serve immediately.