Make sure your oven rack is at the lowest setting
In a medium bowl whisk together 1 cup sour cream, the pumpkin, 4 eggs and the vanilla. Set aside.
Using a stand mixer with the paddle attached mix the flour, sugar baking powder, baking soda and salt.
Add the remaining 1/2 cup sour cream and butter and mix until it starts to look like sand. If a few large pieces of butter remain that is OK. This should take about a minute and a half. Turn the speed to medium and beat until the batter comes together, about 10 seconds, scraping down the bowl if needed.
Reduce to medium low and add the egg/pumpkin mixture in three additions, beating for about 20 seconds after each one. Scrape the bowl as needed
Turn the speed up to medium high and beat until light and fluffy, about 1 minute.
Remove the bowl from the mixer and fold in the dried cranberries.
Place a third of the batter in the bundt pan and sprinkle with half of the streusel mixture. Top with another third of the batter followed by the other half of the streusel. Finish with the final third of the batter.
Gently tap the pan on the counter to settle the batter.
Bake in the preheated oven for 60 - 70 minutes until a tester comes out clean.
Cool in the pan on a wire rack and then invert onto a wire rack to finish cooling completely.
Dust with confectioner's sugar before cutting and serving