Preheat the oven to 350°F. Spray a 10-cup bundt pan with baking spray.
Prep the ingredients: In a small sauce pan, bring the rosemary and milk to a simmer over low heat. Once the milk starts to simmer, remove from heat and let steep while making the rest of the batter. In a small bowl, toss together the cranberries and 1 tablespoon all purpose flour. Remove any excess flour that doesn't stick to the cranberries.
Make the batter: In a medium sized bowl, whisk together the flour, baking powder and salt, set aside. In the bowl of standing mixer with the paddle attachment or in a large bowl with a hand mixer, beat the butter on medium-high speed until pale and fluffy, about 1 minute. Add the brown sugar and granulated sugar and continue to mix until well incorporated, about 2 minutes, scraping down the sides and bottom of the bowl if needed.
With the mixer running on medium speed, add the eggs, sour cream, and vanilla. Stop and scrape down the sides and bottom of the bowl if needed.
Reduce the speed to low and add the dry ingredients. Once the dry ingredients are mostly incorporated, remove the rosemary springs from the milk and pour the milk into the batter. Gradually increase speed to medium so the milk doesn't spill over the sides of the bowl. Mix on medium speed until fully combined, about 1-2 minutes.
Using a spatula, fold in the cranberries. Transfer the batter to the greased bundt pan and bake for 55-70 minutes or until a toothpick inserted near the center comes out clean.
Allow the cake to cool for at 20 minutes before turning out onto a flat surface. The cake should be mostly cool when applying the white chocolate ganache. The warmer the cake, the more the glaze will run.
Prepare the glaze: In a small saucepan, bring the heavy cream to a simmer over low heat. Pour the chocolate chips into a small bowl, when the cream comes to a simmer pour the cream over the chocolate chips, cover with plastic wrap or a clean towel and let sit for 5 minutes. After 5 minutes, stir the chocolate chips and heavy cream until smooth. Let the white chocolate ganache sit until room temperature, about 15 minutes.
Pour the glaze over the cranberry rosemary bundt cake and let it slip down the sides. Serve immediately or let the glaze cool and then cover and refrigerate until serving.