📖 Instructions

1. Before you even think about mixing, take your butter out of the fridge. Seriously, let it sit on the counter for about 30-45 minutes. Room temperature butter is *crucial* for a smooth, creamy dough. No cold, hard butter allowed here!
2. In a large bowl, or the bowl of your stand mixer, cream together the softened unsalted butter and granulated sugar until it’s light and fluffy. This usually takes about 2-3 minutes on medium speed. Scrape down the sides of the bowl often, ensuring everything gets mixed in properly.
3. Now, crack in that large egg and pour in the vanilla extract. Beat everything together until it's just combined. Don't overmix at this stage; we just want it nicely incorporated.
4. In a separate medium bowl, whisk together the all-purpose flour, baking powder, and a pinch of salt. Whisking ensures everything is evenly distributed so you don't get a random pocket of salt in one cookie.
5. Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. The dough should come together and be soft, but not sticky. Be careful not to overmix the dough, as that can make your cookies tough. Once it looks like a cohesive dough, stop.
6. Divide the dough in half. On a lightly floured surface, or between two sheets of parchment paper (my favorite trick for less mess!), roll out one half of the dough into a rectangle, roughly 12x9 inches and about 1/8 to 1/4 inch thick. Try to get those edges as straight as you can.
7. In a small bowl, mix together the cinnamon and granulated sugar for the filling. This is where the magic happens! Be generous with your cinnamon; it's the star of the show.
8. Sprinkle half of the cinnamon-sugar mixture evenly over the rolled-out dough rectangle, leaving a small border (about 1/2 inch) around the edges. Gently press the sugar into the dough with your fingertips or a rolling pin.
9. Starting from one of the longer sides, carefully but firmly roll the dough up tightly into a log. You want it to be as tight as possible to get those beautiful, defined swirls. Repeat this process with the second half of the dough and the remaining cinnamon-sugar filling.
10. Wrap each dough log tightly in plastic wrap. Now comes the important part: pop them into the refrigerator for at least 1 hour. This chilling time helps the dough firm up, making it easier to slice and preventing the cookies from spreading too much during baking. If you've got the time, 2-3 hours, or even overnight, is even better!
11. Once the dough is nicely chilled, preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper. This makes for easy cleanup and prevents sticking.
12. Take one chilled dough log and, using a sharp knife, slice it into 1/4-inch thick rounds. Don’t try to rush this step; nice, even slices mean evenly baked cookies. If your knife gets sticky, wipe it clean between slices.
13. Place the sliced cookies about 1 inch apart on the prepared baking sheets. They don't spread a ton, but a little room gives them space to breathe.
14. Bake for 10-12 minutes, or until the edges are lightly golden brown. Keep an eye on them, as oven temperatures can vary! You want them set, but still soft in the center.
15. Let the cookies cool on the baking sheets for about 5 minutes before carefully transferring them to a wire rack to cool completely. This helps them firm up and prevents them from breaking. Don’t try to move them too soon, they'll be a bit delicate.
16. Once cool, stack 'em up or plate 'em pretty! These cookies are best enjoyed fresh, but they store well too. Get ready to enjoy those perfect swirls and amazing flavor!