Sift together the cake flour, baking powder, and salt into a medium bowl. Set aside. This ensures even distribution of leavening agents throughout your French butter cookies and prevents lumps in the final dough.

In a large mixing bowl, work the softened butter with a spatula or mixer until completely smooth and creamy. The butter should be pliable but not melted-proper temperature is crucial for achieving the perfect La Grande Galette texture.

Gradually incorporate the powdered sugar into the butter. Mix gently and deliberately-avoid over-aerating, as these butter cookies French style rely on baking powder for lift rather than incorporated air. Continue mixing until the mixture is smooth and fully combined.

Add the 3 egg yolks in three separate additions, mixing thoroughly after each addition until the mixture is completely smooth and homogeneous. This gradual incorporation prevents the mixture from splitting and ensures a silky dough.

Add all the sifted dry ingredients at once. Mix until mostly combined-some unmixed flour patches are acceptable at this stage. Avoid overmixing to maintain the tender, delicate crumb characteristic of authentic French butter cookies.

Pour in the dark rum and mix until the dough comes together evenly. Finish mixing with a spatula, scraping down the sides and bottom of the bowl to ensure no dry spots remain. The dough should be soft but cohesive.

Place the dough between two sheets of parchment paper. Using leveling bars or rolling guides, roll the dough to an even 1 cm (about 0.4 inches) thickness. Consistent thickness ensures uniform baking across all your La Grande Galette French butter cookies.

Refrigerate the rolled dough (still sandwiched between parchment) for approximately 2 hours until completely firm. This chilling period is essential for clean cutting and shape retention during baking.

Preheat your oven to 170-180°C (338-356°F). Remove the chilled dough from the refrigerator. Use a round cookie cutter (about 5.6-5.7 cm diameter) to cut circles. Gather scraps, re-roll between parchment, and cut additional cookies-waste nothing!

For perfectly round, tall French butter cookies, place each cut cookie inside slightly larger tart rings (6 cm diameter) positioned on a parchment-lined baking sheet. This technique encourages upward expansion while preventing sideways spreading.

Brush the tops of each cookie generously with the remaining egg yolk (use pure yolk for that signature glossy golden color). This creates the beautiful sheen characteristic of bakery-quality famous French cookies.

Using a fork, gently score a crisscross or lattice pattern on the top of each cookie. Press lightly-this decorative touch is traditional for La Grande Galette presentation.

Bake in the preheated oven for 15-20 minutes (timing varies with thickness and oven calibration; begin checking at 12-15 minutes). The cookies should develop a golden-brown top and edges. Avoid overbaking-they will firm considerably as they cool.

Allow the French Butter Cookies La Grande Galette to cool completely on the baking sheet, as they’re quite fragile when hot. They’ll crisp up beautifully during the cooling process, developing that perfect sandy texture.