In a small bowl, combine the flour, baking soda and salt.
In a large bowl with the paddle attachment, cream the sugar and butter until the color lightens and it's fluffy, about 2 minutes.
Add the eggs and mix well to combine. Add the sour cream and vanilla and mix on low until well combined. Scrape the sides and bottom of the bowl as needed,
Add the dry ingredients mix on low until the batter is just combined.
Thoroughly coat a 9 or 10 inch bundt pan with nonstick cooking spray or softened butter. Dust with almond or all purpose flour. Tap out any excess flour.
Pour half of the batter into the prepared pan. Sprinkle half of the cinnamon-walnut filling evenly over the batter.
Add the remaining batter and use a spatula to spread it evenly. Sprinkle the remaining cinnamon filling mixture on top, spreading evenly
Bake for about 70 minutes, until a skewer comes out clean. Cool the cake in the pan for 15 minutes. Put a cooling rack on top of the pan and invert the pan. The cake should release easily.