Adjust oven rack to lower-middle position and heat oven to 350 degrees. Grease 12-cup Bundt pan and dust with flour.
Whisk flour, nuts, confectioners' sugar, baking soda, and salt in large mixing bowl.
Beat eggs and vanilla in large measuring cup.
With electric mixer on medium-high speed, beat granulated sugar, brown sugar, and butter until light and fluffy, about 2 minutes.
On low speed, add egg mixture until combined, about 30 seconds. Beat in flour mixture until just combined, about 30 seconds.
Scrape the batter into the prepared pan and smooth with a spatula.
Bake until edges are beginning to pull away from pan, about 60 minutes. Cool upright in pan on wire rack for 1 hour, then invert onto serving plate and cool completely, at least 2 hours.
Once cake has cooled, slightly heat remaining caramel filling on stove top or in microwave, stir and pour over cake.
Serve and enjoy every bite.