Preheat the oven to 356°F/180°C. Grease an 8-inch round pan with butter and set aside.
Melt the butter in a pan and add the cane sugar. Cook until the mixture gets bubbly. Spread it evenly on the bottom of the cake pan and top with sliced kumquats. Try to fill every empty space with a piece of kumquat, as they shrink when baked in the oven. Set aside.
In a small bowl, mix together the flour, salt, baking soda, and set aside.
In a large bowl, cream together the cane sugar and butter. When combined, add the greek yogurt and egg.
Add the dry ingredients into the wet ingredients and stir until just combined. Pour the batter over the sliced kumquats and top with the sliced almonds.
Bake for 30 minutes, or until a toothpick inserted comes out clean. Let the cake cool for 10 minutes before inverting onto a plate.