Bring 0.5 cups sugar and water to a simmer in a saucepan. Simmer until sugar is completely dissolved.

Pour simple syrup into a heatproof bowl and allow to cool for about 10 minutes.

Add cranberries and stir to coat. Refrigerate cranberries in syrup overnight, stirring a couple of times to coat.

Prepare a bundt pan with baking spray. Preheat oven to 350°F.

In a large bowl, cream butter and 1.5 cups sugar until light and fluffy, about 3-4 minutes.

Add sour cream and vanilla, mix until combined.

Add eggs in two batches, mixing well after each addition. Scrape down sides as needed.

Combine dry ingredients in a bowl. Mix milk and water in a small cup.

Add half of dry ingredients, then milk mixture, then remaining dry ingredients, scraping sides as needed.

Gently stir in 2.5 cups cranberries.

Pour batter into prepared pan. Bake for 47-50 minutes.

Cool in the pan for 15-20 minutes, then turn out onto a rack to cool completely.

Make ganache: heat heavy cream until boiling, pour over white chocolate chips, and whisk until smooth. Cool slightly.

Drizzle ganache over cooled cake.

Remove sparkling cranberries from syrup, roll in remaining sugar, and let dry for 30-60 minutes.

Top the cake with cranberries and refrigerate until ready to serve.