Preheat the oven to 350ºF/177°C.
Prepare a loaf pan with parchment paper.
Separate the egg yolks and egg whites into 2 different bowls.
In a mixing bowl, sift together cake flour, baking powder, baking soda, and salt. Set aside.
In a food processor, add the butter, almond flour, almond paste, sugar, 4 egg yolks, vanilla extract and almond extract one ingredient at a time, processing until the mixture becomes very creamy, about 5 minutes. Do not over process as the butter may melt.
Transfer the creamed almond mixture into a mixing bowl and set aside.
In a clean stand mixer bowl fitted with a wire whisk, whip the 4 egg whites and and cream of tartar until foamy, and add in the sugar gradually, whipping until very stiff peaks.
Alternate adding the flour mixture, milk and whipped egg whites into the creamed almond mixture in 3 batches.
Use a spatula to fold the mixture until just incorporated.
Pour the batter into the prepared pan. Tap the pan to release any trapped air bubbles.
Bake the cake at 350ºF/177°C for 60-65 minutes or until a toothpick inserted comes out clean.
Remove the cake out of the oven and let the cake cool in the pan on a wire rack for 15 minutes.
Then gently remove cake out of the pan and let it cool completely.