1. To make the cranberries, bring 1/2 cup sugar and the water to a simmer in a saucepan. Simmer until sugar is completely dissolved.
2. Pour simple syrup into a heatproof bowl and allow to cool for about 10 minutes.
3. Add cranberries and stir to coat.
4. Refrigerate cranberries in syrup overnight, stirring a couple times to coat with syrup.
5. Prepare a bundt pan with baking spray. Preheat oven to 350°F (176°C) .
6. In a large mixing bowl, cream butter and sugar together until light in color and fluffy, about 3-4 minutes. Do not skimp on the creaming time.
7. Add sour cream and vanilla extract and mix until well combined.
8. Add eggs in two batches, mixing until well combined after each. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
9. Combine dry ingredients in a separate bowl, then combine the milk and water in a small measuring cup.
10. Add half of the dry ingredients to the batter and mix until well combined. Add the milk mixture and mix until well combined. Add remaining dry ingredients and mix until well combined. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
11. Gently stir in the cranberries.
12. Pour the batter evenly into the prepared bundt pan.
13. Bake for 47-50 minutes.
14. Remove the cake from the oven and allow to cool in the pan for about 15-20 minutes.
15. Turn the cake out onto a cooling rack to cool completely.
16. To make the white chocolate ganache, place the white chocolate chips in a large bowl.
17. Heat the heavy whipping cream until it begins to boil, then pour it over the white chocolate chips. Allow to sit for 2-3 minutes, then whisk until smooth. If it doesn’t get completely smooth, microwave in 10-15 second increments, whisking in between each increment, until smooth.
18. Set ganache aside to cool slightly. You want it to still be pourable, but thick enough that it won’t all just slide down the sides of the cake.
19. Drizzle the ganache over the top of the cake. Set cake aside.
20. Remove the sparkling cranberries from the syrup and roll in the remaining cup of sugar. You’ll need to roll them a few times to get a couple layers of sugar on them. Set cranberries aside to dry for about 30 minutes to an hour.
21. Top the cake with the sparkling cranberries. Refrigerate until ready to serve.