1. Preheat oven to 350 degrees
2. Prepare an 8×3 inch springform cake pan using a round piece of parchment paper on the bottom and Bakers Joy baking spray on the sides.
3. Whisk together flour, sugar, baking soda and baking bowl in a large mixing bowl.
4. Add butter, egg, vanilla, sour cream and milk and mix on medium speed until combined and smooth.
5. Pour batter into cake pan and bake for 45-50 minutes, or until a toothpick comes out with a few crumbs.
6. Remove cake from oven and allow to cool for about 10 minutes in the pan.
7. Remove cake from pan and finish cooling on cooling rack.
8. Once cake has cooled, use a serrated knife to cut off the cake dome.
9. Place back into springform pan, lining sides of pan with parchment paper so that it sticks up above the edge of the pan.
10. Put white chocolate chips for truffle layer into a mixing bowl.
11. Microwave heavy cream until boiling, then pour over white chocolate chips.
12. Cover bowl with clear wrap and allow to sit for 5-7 minutes.
13. Whisk mixture until smooth, then allow to cool to room temperature.
14. Add mascarpone cheese and mix until smooth.
15. Pour white chocolate mixture over cake and spread evenly. It will come above the edge of the cake pan, but your parchment paper should be high enough. Refrigerate until firm, 3-4 hours.
16. Once truffle layer is firm, remove cake from pan.
17. Add white chocolate chips for ganache to a medium sized bowl.
18. Microwave heavy cream until boiling, then pour over white chocolate chips.
19. Cover bowl with clear wrap and allow to sit for 5-7 minutes.
20. Whisk mixture until smooth, then allow to cool for 10-15 minutes. The longer it cools, the thicker it will get.
21. Pour ganache over the cake and allow to drizzle down the sizes.
22. Place Lindor truffles evenly around the edge of the cake.
23. Store in refrigerator for up to 5 days. Remove cake from refrigerator 10-15 minutes before serving.