In a large bowl, mix together the all-purpose flour and salt.

Cut in the chilled salted butter until the mixture resembles coarse crumbs, then fold in the active sourdough discard until just combined.

Wrap the dough in plastic wrap and chill in the refrigerator for about 30 minutes.

In a separate bowl, beat together the almond flour, granulated sugar, egg, almond extract, and vanilla extract until smooth.

Roll out the puff pastry on a lightly floured surface to about 1/4 inch thick. Spread the almond frangipane evenly over the surface.

Cut into strips and roll each strip like a spiral.

Preheat your oven to 375°F (190°C).

Place the rolled cruffins in a lined muffin tin, upright. Sprinkle with slivered almonds.

Bake for 30 minutes until golden brown.

Let the cruffins cool slightly in the tin and dust with powdered sugar before serving.