Pulse together flour, salt, and baking powder in a food processor for about 10 seconds to evenly combine the ingredients.

Cut cold butter into 1/2" chunks and add to the food processor along with the vanilla extract and lemon zest. Pulse until mixtures resemble breadcrumbs, about 30 seconds.

Add yogurt and pulse until the dough comes together into a ball, about 10 seconds. Do not over mix. The dough will be sticky.

Turn dough out onto a well-floured surface, cut in fours, and form each piece into a disc. Wrap well and refrigerate for 1 hour or overnight. At this point, the dough can be frozen to use at a later date. Thaw in the refrigerator for 24 hours before proceeding.

To prepare the filling, toast chopped nuts on a parchment-lined baking sheet in the oven for 5 minutes at 400˚F.

Cool nuts at room temperature and mix with brown sugar and cinnamon. The nut mixture can be made ahead of time and stored in an airtight bag or container at room temperature until ready to use.

When ready to assemble cookies, preheat oven to 400˚F and line 4 half baking sheets with parchment paper.

Take one disc of dough out of the refrigerator and roll it to a 1/4" thick round about 9 1/2" in diameter on a well-floured surface. Dust dough, rolling pin, and surface with more flour as needed to keep the dough from sticking.

Spread 1/4 of the jam in a layer over the surface of the dough. Then sprinkle 1/4 of the nut mixture all over the jam.

Cut dough into 12 wedges with a sharp knife or pizza wheel. First, cut dough in half then in quarters, then cut each quart section into thirds.

Use an offset spatula to gently pull a wedge out of the circle and then roll it up from the outer edge to the point. Transfer to a parchment-lined half baking sheet with seam side down.

Repeat steps 8-11 with the second disc of dough.

Brush the tops of the pastry with non-dairy milk and sprinkle with granulated sugar.

Bake the first two sheets on the bottom and top third oven racks at 400˚F for about 20-25 minutes until the pastry is golden brown. Turn sheets halfway through baking. The filling will ooze out a little during baking.

While the first 2 sheets of cookies are baking, prepare the next 2 sheets by repeating steps 8-14.

Allow cookies to cool on sheets for 1 minute before transferring them to cooling racks to cool to room temperature.