01 - Separate egg yolks and whites into two distinct mixing bowls. To the bowl with the egg yolks, add the whole milk and vanilla extract. Whisk until the mixture is thoroughly combined.
02 - Sift the cake flour and baking powder into the yolk mixture. Whisk until a smooth batter forms.
03 - In the separate bowl, add the cream of tartar to the egg whites, if using. Beat with an electric mixer until foamy. Gradually add the granulated sugar while continuing to beat until stiff, glossy peaks form.
04 - Gently fold one-third of the whipped egg whites into the yolk batter to lighten it. Carefully fold in the remaining egg whites, preserving as much air as possible.
05 - Lightly grease a nonstick skillet or griddle with unsalted butter and heat over low heat. For taller pancakes, use lightly greased pancake molds or ring molds.
06 - Spoon the batter into the molds or directly onto the heated skillet, aiming for a height of 2–3 inches. Cover the skillet with a lid and cook slowly for 4–5 minutes, or until the bottoms are golden brown and the tops appear set.
07 - Carefully flip each pancake, using the ring molds if utilized. Cover and cook for an additional 3–4 minutes, or until cooked through and springy to the touch. Remove from molds and repeat the process with the remaining batter.
08 - In a small saucepan over medium heat, melt the unsalted butter. Continue cooking, swirling the pan occasionally, until the butter turns a golden brown color and develops a nutty aroma, approximately 3–4 minutes. Remove from heat and whisk in the pure maple syrup and a pinch of sea salt.
09 - Serve the pancakes stacked, dusted with powdered sugar, and topped with fresh berries, if desired. Drizzle generously with the prepared brown butter maple syrup.