Preheat oven to 350 degrees F. Generously spray a 9" x 5" loaf pan with non-stick cooking spray.
Zest the lemon and place in large mixing bowl. Juice the lemon into a one cup measuring cup and fill the remainder with the cream (half and half or whole milk).
In the large mixing bowl with the zest, add cake mix, yogurt and the measuring cup with lemon juice and cream. Starting slowly, with a hand mixer, mix together the ingredients, then increase speed to high and beat for 3 minutes, scraping the sides of the bowl a few times.
Spoon thick mixture into the prepared loaf pan and smooth the top. Sprinkle top with brown sugar. Bake for 45 - 50 minutes, or until a toothpick inserted in bread comes out clean.
Allow to cool in pan for 15 minutes. Remove and allow to cool completely. Slice