Preheat oven to 350 degrees F. I used an eight inch cake pan, but you can also use a nine inch pan. Place butter in the pan and put in the oven. When the butter is melted, remove the pan from the oven. Using two pot holders, tilt the pan around and around, coating the sides of the pan with butter. Once coated, set aside.
In a medium bowl, whisk together flour, baking powder, baking soda, salt and cardamom. Set aside.
In the bowl of an electric mixer, cream butter and brown sugar on medium speed. Cream until slightly pale and fluffy, approx 3 minutes. Stop mixer, scrape the bowl with rubber spatula, and add in egg and vanilla extract. Beat for about 1 minute.
Turn the mixer off, scrape the bowl and add the dry ingredients. Beat on low speed while adding the sour cream. Beat until the batter just comes together, and it will be pretty thick. Remove the bowl from the mixer and finish incorporating ingredients with the spatula.
Sprinkle 1/4 cup brown sugar into the melted butter in the cake pan. Sprinkle strawberry slices over the butter and sugar in a single layer. Spoon batter over the strawberries and spread evenly with spatula. Bake for about 35 minutes or until inserted toothpick comes out clean. Let the cake rest for about 10 minutes before running a knife around the edge of the cake and inverting the cake onto a cake plate. Serve warm with sweetened sour cream or whipped cream.
To sweeten sour cream:
Add powdered sugar slowly to 2/3 cup sour cream, taste frequently and when sugared to taste, add a dollop to your slice of cake!