In a medium bowl mix together flour, walnuts, salt, and cinnamon.
Using an electric stand mixer beat together butter, sugar, and vanilla over medium speed until pale and creamy. About 5-7 minutes. Add the egg and cream until fully combined. Add the flour/nuts/cinnamon/salt mixture and mix on the very low speed until the flour is just worked into the dough. Do not overmix the dough at this stage as it will make the cookies tough.
Divide the dough into two portions.
Wrap each portion into food plastic wrap and refrigerate for about 30 minutes or until it firms up. When you are ready to roll out the cookies preheat the oven to 350F.
Line baking sheets with parchment paper.
On a lightly floured work surface roll out a portion of dough until it is about 1/8” thick.
Using a cookie cutter cut as many cookies as possible, setting the scraps aside. Place the cookies onto the prepared baking tray and refrigerate for 15-20 minutes. After the cut outs have chilled in the fridge – take small heart shaped cutter and remove the middle from half of the cookies.
Bake for 15-20 minutes until lightly golden.
Allow baked cookies to cool on the baking tray for a couple minutes before transferring to a wire rack to cool completely.
Repeat this process with the second portion of dough.
For the left-over scraps of dough – gently reform them into a ball and then refrigerate for about 10-15minutes to let it firm up. Once it has firmed up proceed with rolling out the dough and cutting out cookies in the same manner as described above.
To assemble sandwiched cookies, place a little bit of jelly onto each base cookie and spread slightly towards the edge.
Dust all the top cookies with powdered sugar and sandwich two cookies together.