1/3 cup blackberry jelly (or other jelly or jam of your choice) → equivalent to 1 teaspoon per sandwich (16 teaspoons total)
In the bowl of an electric mixer fitted with a paddle attachment, beat together butter and brown sugar on medium speed until light and fluffy, about 3 minutes. Scrape down the sides of the bowl; add egg yolks and vanilla and beat to combine.
In a separate bowl, mix together flour and salt. Add flour mixture to butter mixture. Beat until combined (should look like wet sand).
Turn dough out onto work surface; knead a few times until the dough comes together into a ball.
Divide dough in half. Set each half on plastic wrap or parchment paper and form into a 7” by 1.5” log. To shape the log like bread, square off the bottom of the log but allow the top to stay grounded. Take the long side of a ruler and make an indent about 1/3 of the way down from the top of the log; the indentation should run the entire length of the log and be well-defined enough to withstand baking. Repeat on the other side of the log. Take the ruler and make a slightly lighter indentation along the top of the log. Repeat process with another log of dough. Wrap tightly in plastic or parchment paper and let refrigerate for at least an hour, or overnight.
Preheat the oven to 350F. Line 2 baking sheets with parchment and set aside.
Remove dough from refrigerator and unwrap. In a small bowl, combine granulated sugar and cinnamon. Sprinkle cinnamon sugar mixture over logs of dough; using your hands, rub mixture into top and sides of the log. All sides should be coated.
Using a very sharp knife, slice logs into 1/4” thick pieces. Lay slices on parchment paper about an inch apart. Bake for about 15 to 18 minutes, rotating the baking sheets halfway through until the cookies are golden brown around the edges. Remove from oven and let cool on baking sheets for about 5 minutes. Transfer to cooling racks and cool the rest of the way.
Once cookies are cooled, it’s time to assemble the sandwiches! Take 2 cookies and lay them with the flatter side facing up (the side that was against the baking sheet). Put 1 teaspoon each of almond butter and jelly on either cookie; join both halves. The filling will ooze out of the cookie; if you want them to be a little less messy, cut back on the fillings. Repeat filling process with remaining cookies.