In a large bowl, whisk together the cake flour, cocoa powder, and salt until well combined, and no lumps remain.
In the bowl of a stand mixer fitted with the paddle attachment (or using a large bowl and a hand mixer), cream butter, the Redpath® Dark Brown Sugar, and Redpath® Icing Sugar on medium speed until pale in colour; 2 minutes.
Add in the egg yolk and pure vanilla extract. Blend until fully incorporated into the butter mixture.
Add in half of the dry ingredients. Mix on low speed until just combined. Repeat with the remaining dry ingredients. Mix on low speed until dough is no longer crumbly and holds together; do not overmix.
Line 2 baking sheets with parchment paper.
Using a small, trigger-style ice cream scoop, scoop 1½-inch diameter balls (approximately 20 grams) onto the prepared baking sheets (see Chef’s Tips). Roll each ball in the palm of your hand until smooth and roughly spherical.
With the handle of a wooden spoon dipped into a small dish of water (this prevents the handle from sticking to the dough), make an indentation into each ball (about ½ inch deep and ¾ inch wide).
Place chocolate sprinkles into a small dish. Carefully press and roll the tops and sides of each cookie into the chocolate sprinkles; this creates the “nest.”
Space cookies about 2 inches apart on the baking sheets and place into the fridge to chill; at least 30 minutes. Preheat the oven to 375°F (190°C).
Place the chilled cookies into the preheated oven. Bake for 8 to 10 minutes or until bottoms and edges are golden in colour. Tops should still be relatively pale.
Allow to slightly cool on the pan before transferring to a wire cooling rack to cool completely.