For the cake:

1. Preheat oven to 350ºF/180°C.
2. Brush a 9 or 10 cup (26cm) bundt pan with shortening (not butter), covering every angle and surface, and coat with flour, shaking off excess. Put the pan in the refrigerator while making the batter. This is my way of preparing the bundt pan. Alternatively, spray with baking spray that has flour in it or use cake goop (google it, there are many recipes).
3. Transfer 2 tablespoons from the total flour amount and put them in a bowl. They will be used to coat the raspberries right before adding them to the batter so they don't sink to the bottom. 
4. Sift the rest of the flour, baking powder and salt. Set aside. I have the ingredients measured and sift them directly over the batter. 
5. In a large bowl, beat butter until creamy. Slowly add sugar and beat for 2 minutes. Use an electric mixer or a stand mixer with the paddle attachment. 
6. Add eggs one at a time, beating well after each addition, and then beat for 1 minute.
7. Beginning and ending with dry ingredients, add them in 3 parts alternating with buttermilk and vanilla in 2 parts.
8. Fold in raspberries with the reserved flour and add to the batter, together with the lemon zest and white chocolate, and mix with a spatula a few turns. Don't use the beater, and don't mix it too much. We want the chocolate to be incorporated but the raspberries to remain whole, coated as much as they can in flour, and not stain the batter much.
9. Pour the batter into the prepared bundt pan, spreading evenly.
10. Bake about 45-50 minutes, or until a tester inserted in center comes out clean. It might take more depending on the oven and pan you're using. 
11. Let cool for 10 minutes on a wire rack and then move and lightly shake the pan grabbing it by the sides with both hands (and a kitchen towel since it's hot!). That way the cake starts to loosen. If it doesn't I use a small smooth bladed knife to separate the batter from the sides and center. The raspberries sometimes stick to the walls of the pan.
12. Once you make sure it can be removed, do so over a wire rack and let cool completely.

For the frosting:

1. Finely chop white chocolate and put in a bowl.
2. Heat cream until it is about to get to the boiling point, remove and add immediately to the chocolate, covering it. It will seem too much chocolate for so little cream, and there is a point there. But it will melt and you will be able to mix it. We want a thick ganache, and for that we need more chocolate than cream. 
3. Let stand for a minute and whisk until smooth. If bits of chocolate remain, microwave in 5-10 seconds bursts and whisk every time until the mixture is smooth.
4. Put the cold cake on a wire rack with a parchment paper underneath or on a smooth surface like the kitchen counter or marble. 
5. Let the ganache cool until it thickens a little but it's still pourable. Otherwise it will be too thin. Pour over cold cake and let it drip down the sides. It will drip onto the paper or surface. Most times I do scrape the drippings up into the bowl and use them again to add a second layer or fill some holes or thin parts. You can also pour half of the ganache, wait a little until it almost stops dripping and then pour the other half. That will create a thicker layer of glaze. 
6. Decorate with chopped or whole raspberries if you want. I used frozen for the photo because it was Winter, but I try to use fresh if I can. Keep in mind that most berries lose their shine and start releasing liquid, so decorate right before you serve it for best results.