Ingredients
Scale
- 4 oz (1 stick) unsalted butter, softened to room temperature
- ½ cup light brown sugar, packed
- ¼ cup granulated white sugar
- 1 medium egg (≈50 g), at room temperature
- 1 tsp vanilla extract
- 245 g all-purpose flour (about 2 cups by volume — see notes)
- ¼ tsp kosher salt
- ¼ tsp baking soda
- ½ tsp cream of tartar
- For rolling: ⅓ cup granulated sugar mixed with 2 tbsp ground cinnamon
- For the eggnog ganache: 4 oz white chocolate, chopped into small pieces
- 2 tbsp eggnog
- 1 tbsp dark rum (or ¼ tsp rum extract) — optional
- ¼ tsp freshly grated nutmeg
Instructions
- Preheat the oven to 350°F (175°C). Line baking sheets with parchment or silicone mats.
- In the bowl of a stand mixer fitted with the paddle (or use a hand mixer), beat the softened butter with both sugars until the mixture lightens in color and becomes fluffy. Scrape the bowl once or twice while you work.
- Add the egg and vanilla, then mix until smooth and evenly combined. Scrape down the sides as needed.
- In a separate bowl, whisk together the flour, cream of tartar, baking soda, and salt. If any clumps appear, sift or whisk well.
- Add the dry ingredients to the butter mixture and stir until a soft dough forms. Stop when everything just comes together — don’t overwork it.
- Portion the dough into roughly 1-tablespoon balls (about 15 g each). Roll each ball in the cinnamon-sugar mixture so they’re evenly coated. Place them a couple of inches apart on the prepared sheets.
- Make a shallow well in the center of each ball using a ½ teaspoon or your thumb (short nails help!). If a cookie cracks while you press, press the edges back together gently.
- Bake for approximately 7 minutes. The cookies should have set edges but still look slightly soft in the center. If any indents puff up during baking, press them gently again while the cookies are warm.
- To make the filling: place the chopped white chocolate, eggnog, and rum (if using) in a microwave-safe bowl. Heat in 15-second bursts, stirring between each, until the chocolate is fully melted and the mixture is smooth. (Use a double boiler if you prefer.) Stir in the grated nutmeg. The ganache will be loose when hot and will thicken as it cools. Heat slowly to avoid seizing.
- Spoon about ½ teaspoon of ganache into each thumbprint. Let the cookies sit at room temperature for a few hours until the filling firms to a soft, fudge-like texture. If you want them set faster, chill briefly in the fridge.
Notes
- Storage & Serving
- Once cooled and filled, store cookies in an airtight container at room temperature for up to 5 days. You can freeze baked cookies (well wrapped) for up to 3 months—place wax or parchment between layers when stacking. Thaw overnight in the refrigerator.
- Notes & Helpful Tips
- Egg size matters. This recipe calls for a medium egg. Using a much larger egg will change how the dough behaves.
- Butter choice matters. I use regular American-style butter (not high-butterfat European-style). If you switch to a European butter, expect more spread.
- Butter temperature matters. Your butter should be soft but still slightly firm — not greasy or melted. Too-soft butter = more spreading.
- No chilling required. These cookies hold their thumbprints without refrigeration, but you can shape and chill the dough ahead if you want. Chilling helps keep shape but isn’t mandatory.
- Rum is optional. If you don’t want alcohol, simply leave the rum or extract out—no substitution needed.
- Weigh your flour if you can. 245 g is the target. If you measure by volume, spoon and level the flour into your cup for best results. Too much flour = dry, crumbly cookies; too little = cookies that spread and lose their indents.
- Microwave ganache carefully. Heat in short intervals and stir between bursts to prevent the chocolate from seizing. FYI: good-quality white chocolate (bar, not chips) gives a silkier ganache.