sweetheart sablés

Make dough in a food processor: Combine the flour, sugars, and salt in the work bowl. Add cold, diced butter and mix or pulse until it disappears, then keep running the machine until it just begins to clump. Add egg yolk (save the egg white for later) and vanilla and pulse until combined, then keep running the machine until the dough forms one large or a couple smaller masses.

Make dough in a stand mixer or with a hand mixer: Combine butter, sugars, and salt in a large bowl, or the bowl of your stand mixer and beat until creamy. If you began with cold butter in a stand mixer, this will take a couple minutes and require you to scrape down the bowl a few times. Once mixture is thoroughly combined, add egg yolk (save the egg white for later) and vanilla and beat until combined. Add flour and beat until it disappears into a smooth dough.

Both methods: Divide dough into 2/3 and 1/3 portions. [The total dough weighs about 615 grams; 2/3 will weight 410 grams; 1/3 will weigh 205 grams.] Cover the larger potion loosely with plastic so it doesn’t dry out and leave it at room temperature. Tint the smaller portion a color of your choice, or divide it again [100 grams each] and tint it two different colors. To marble two colors back together, place large pinches of dough in a rough checkerboard pattern on a piece of parchment paper. Use the parchment to fold this dough mess in half once and pat it back flat. Repeat in a second direction, folding and patting flat, for further marbling. Err on the side of under-marbling, as the colors will be further chopped and mixed in the next step.

Form hearts: Roll tinted dough between two pieces of parchment paper. You can go fairly thick here [1/4 to 1/2-inch], as long as you can still comfortably cut shapes out. Slide parchment onto a board or plate, so it’s solid underneath, and transfer the board and dough to the freezer until the dough is firm, about 5 to 10 minutes.

Remove top sheet of parchment and place it gently back on the slab of cold dough. Flip dough onto this loosened paper and peel back and remove what is now the top sheet. Save the top parchment; we will use it. Cut tinted slab into as many 1-inch hearts as you can. Stack them on top of each other, pressing them gently so they adhere. Once you’ve cut as many as you can, place this heart-shaped column on the spare piece of parchment, and slide it back into the freezer until solid, about 10 to 15 minutes. Remove the heart column from the freezer and use the parchment to give it a few extra presses, making sure the hearts are adhered to each other.

Form final cookie log: Use the remaining untinted cookie dough to wrap the heart column. I found it easiest to make several coils the length of the heart column and press and smooth them onto it. Once the heart column is fully wrapped in untinted dough, roll it in parchment to smooth the sides and pressed tightly against the center column. Freeze this log until solid, 30 minutes.

Slice and bake the cookies: Heat oven to 350°F (175°C). Lightly beat the reserved egg white until loose. Unwrap the chilled log of cookie dough and brush it with egg white. Pour color sugar or sugars of your choice on a small rimmed plate for dipping. Line a large baking sheet with parchment paper. Gently cut the log into just shy of 1/4-inch slices. Roll the edges of each cookie slice in the colored sugar(s) and arrange on the baking sheet, 1 inch apart.

Bake for 9 to 11 minutes, until golden brown underneath. Let cool on baking sheet for 1 minute, then transfer to cooling racks to cool completely.

Do ahead: Baked, cooled cookies keep for 3 weeks in a tin at room temperature. The log of dough will keep, well-wrapped, in the freezer for 1 to 2 months. I’d wrap it in parchment then 1 to 2 layers of plastic.