Preheat oven to 350°F / 180°C and line a cookie sheet with parchment paper.
Cream the butter and both sugars together until combined.
Add the egg and beat until smooth.
In a small bowl, mix together the buttermilk, vanilla, and red food coloring until well combined. Pour into the cookie dough and mix until combined.
In a large bowl, sift the dry ingredients and mix together. Add to the cookie dough and mix until a dough forms and there are no lumps of flour.
Add the chocolate chips and stir until evenly distributed.
Using a medium cookie scoop, or a tablespoon, roll balls of cookie dough onto the prepared cookie sheet. Make sure they are well spaced out to allow room for spreading.
Bake for 12-14 minutes, then remove from the oven and let them sit on the cookie sheet for at least 10 minutes before attempting to move them to a cooling rack.
Optional: Once cooled, drizzle a little melted white chocolate on top for decoration.
Notes
Red Food Coloring: It is important to use gel food coloring. The liquid kinds you can get at the grocery store won't be strong enough to color your dough. The amount of color you need will vary depending on the brand. Start with ¼ teaspoon and add more if necessary. Note that the cookies will darken substantially once the cocoa powder is added to the dough. Cookie Scoot: These cookies should come out fairly round, but if you want to make them absolutely perfect, use a round cookie cutter to 'scoot' round the edges of the cookies as soon as they come out of the oven for perfect circles. Note: For best results, I always recommend weighing your ingredients with a kitchen scale rather than a measuring cup. It's very difficult to get accurate measurements with cups, which can often lead to disappointing results in baking. All my recipes provide the measurements in both cups and grams so you can choose what works best for you.