Pistachio Vanilla Butter Bundt Cake

I've been on a mission lately to use up stuff in my pantry (it tends to get overstocked somehow, especially with baking items...); combine this with desire to make a cake and use up some leftover buttermilk, I landed on this recipe on another person's (Melina) baking blog.
Here is the link to the blog/original recipe:
http://www.sugaryandbuttery.com/2014/04/pistachio-vanilla-butter-bundt-cake.html

As with nearly everything I try, I ended up with a few modifications--and one of them was not intentional (will explain that when I get to it in the preparation steps).

Ingredients:

Vanilla batter--
3 c. all purpose flour
2 tsp. baking powder
1 tsp, baking soda
pinch of salt
1 1/2 c. sugar
1 1/2 sticks of unsalted butter (room temp)
3 large eggs (room temp)
Seeds scraped from 1 vanilla bean:

1 c. buttermilk

Pistachio batter--
1 c. all purpose flour
1/2 tsp. baking powder
1/2 c. sugar
1/2 stick of unsalted butter (room temp)
1/2 c. buttermilk
1 1/4 c. finely ground pistachios

Drizzle frosting--
2 T. melted butter
2 c. powdered sugar
3 T. milk (more if thinner consistency desired)
splash of vanilla extract

1. Preheat oven to 350°F.  Spray a Bundt pan with non-stick spray (I do this and then use paper towel to rub it around/coat evenly).
2. For the vanilla batter, start with whisking the dry ingredients together in a separate bowl.
3. In the mixer bowl, cream sugar, butter, and the vanilla bean seeds (beat until light and fluffy).
4. Add eggs, one at a time, beating well after each addition.
5. Add 1/3 of dry ingredients, mix, add 1/3 of buttermilk, mix--repeat process until all of both are added in and just combined (do not overmix):

6. For the pistachio batter, the process is the same as the vanilla frosting, only the pistachios go in where the vanilla bean is in that one.  You may also notice there is no egg listed in this one; the original recipe lists 1 egg in the ingredients for this part, but the instructions did not, so I ended up omitting it.  Since the cake still turned out great, it may not be entirely necessary.  I'll have to try making it with the egg next time and write a follow-up (this will be sometime far in the future, am guessing, as I have many, many things I want to make before I repeat!).  The batter for this turned out thicker, given it was missing the egg:

7. The original recipe called for the pistachio batter to be layered in-between the vanilla.  I opted to treat it like a marble cake, thus I put the vanilla batter in first and spooned the pistachio out over the top of it:

8. I then swirled the batter into the vanilla with an icing spatula:

9. Baked it for 1 hour, came out looking like this:

10.  Allow it to cool for about 15-20 minutes before turning out on a cooling rack to cool completely.
11.  Once it is cooled, prepare the drizzle icing.  This part is only in my version of the recipe/my modification; in the original, it appears she topped the cake only with a dusting of powdered sugar (no instruction to do so at the end of recipe, just see it in the pictures).  I like a nice drizzle frosting for a Bundt cake, personally, but I think a canned vanilla frosting could go well on this, too, if you prefer.

Drizzle icing instructions:
Melt butter in a medium sized bowl.  Whisk in a little powdered sugar and then a little milk, alternating between each until all have been added.  Whisk in splash of vanilla extract at the end.

12. Drizzle the icing all over the cake; it will drip down over the sides if you simply aim for the middle part of the cake top as you go around it.  Finished product should look something like this:

13. Cut a slice out and enjoy!