Center a rack in the oven and preheat it to 375 degrees F. Line each cavity of the muffin pan with a paper muffin cup.
Place the butter in the bowl of an electric stand mixer or a large mixing bowl. Use the flat beater attachment or a hand-held mixer to beat the butter until light and fluffy, about 2 minutes.
Add the brown sugar and granulated sugar to the butter, and cream together well. One at a time, add the eggs to the butter mixture, stopping to scrap down the bottom and the sides of the bowl after each addition. At first the mixture may look curdled as the eggs are added, but as your stop and scrape down the bowl, the mixture will smooth out.
Use a fork to mash the bananas in a bowl. Add the sour cream and vanilla and mix together well. Add to the butter mixture and blend thoroughly.
Sift together the flour, whole wheat flour, baking powder and baking soda. Add the cinnamon, salt, nutmeg and cardamom and blend together.
Add to the banana/butter mixture in 3 stages, stopping after each addition to scrape down the sides of the bowl to promote even blending. Add the almonds to the batter and stir to distribute evenly.
Use a spoon to divine the batter evenly among the muffin cups, filling them to the top. Bake the muffins for 25 to 30 minutes, until the are light golden brown and a tester inserted in the center comes out clean. Remove the pan from the oven and cool on a rack.