Prepare the nut filling by mixing dark brown sugar, cinnamon, cocoa, chopped raisins, and chopped toasted walnuts in a small bowl. Set aside.

Preheat the oven to 350°F (175°C).

Butter a 10-inch Bundt pan.

In a large bowl, sift flour, baking soda, baking powder, and salt.

Using a stand mixer with a paddle attachment, cream the butter.

Add 2 teaspoons of vanilla extract and sugar and beat on medium speed for 1-2 minutes until light and fluffy.

Add eggs, one at a time, beating until each is just incorporated.

Scrape down the sides of the bowl as necessary.

Beat at high speed for about 1 minute until the mixture is light and creamy.

Turn the mixer to low speed.

Add the dry ingredients in three additions, alternating with the sour cream in two additions, beating only until smooth after each addition.

Spread a thin layer of batter in the bottom of the prepared pan.

Top with 1/3 of the nut mixture.

Repeat layers of batter and nut mixture until you have 4 layers, ending with a batter layer on top.

Bake for 50-60 minutes, or until a cake tester inserted into the center comes out clean.

Remove from the oven and cool for 5 minutes.

Turn the cake out onto a rack and then re-invert it.

Combine confectioners' sugar, hot milk, and the remaining 1 teaspoon of vanilla extract in a small bowl.

Mix well until the glaze has a thick cream sauce consistency.

Place wax paper under the cooling rack.

Pour the glaze over the warm cake, letting it run down the sides.

When the glaze is set, transfer the cake to a serving plate.

Serve warm or at room temperature.