Preheat oven to 356º F (180° C). Grease and line a round baking pan (or bundt cake pan) of approximately 9.85 inches (25 cm) in diameter with parchment paper.
In a medium bowl, sift together the flour with baking powder, baking soda and salt. Separately, cut very small or grate 1/3 part (57 gr) of the white chocolate and set aside in the refrigerator until needed.
Melt 2/3 (3.98 oz) (113 g) of the white chocolate, which can be done in two ways. The first is in a double boiler, placing a medium saucepan with plenty of water over medium heat. Then, add the chocolate to a large heat-resistant bowl and place it on top of the pot with water (without touching the water) so that it melts with the steam.
The second is in the microwave, adding the chocolate to a large microwave-safe bowl and then melting it for 30-second intervals, i.e., put the bowl in the microwave for 30 seconds and take it out after this time to mix a little with a fork. Repeat the process until the chocolate is completely melted.
In a large bowl, add the butter with the sugar and beat with a hand whisk or an electric mixer for 2-3 minutes until the mixture is light and fluffy.
Beat with an electric mixer for 2-3 minutes until you get a lighter and fluffier mixture. Add the eggs one at a time, beating for 30 seconds after each addition. Add the vanilla extract, almond extract, melted chocolate and beat until well blended. Add the sour cream and beat for 1 minute more until very smooth.
Add the flour mixture in 2 separate additions, alternating with the milk and beating after each addition. Beat for 20 seconds until smooth and homogeneous. Add the grated chocolate and mix with a rubber spatula just until incorporated.
Pour the mixture into the pan and spread it with the rubber spatula to make it uniform. Bake at 356º F (180° C) for about 50 minutes to 1 hour until a wooden toothpick comes out clean when inserted.
Once the pound cake is ready, take it out of the oven, let it rest for 10 minutes inside the pan and then turn it out and place it on a rack to cool for at least another 10 minutes.