Step 1: Preheat oven to 350°F (175°C). Lightly grease an 8 1/2″-x-4 1/2″ loaf pan. Line with parchment paper, leaving enough overhang to use as handles, then grease paper.
Step 2: In a large bowl, whisk together both flours, baking powder, baking soda, cinnamon, cardamom, and salt.
Step 3: In a large bowl, with hand mixer or whisk, combine brown sugar, molasses, eggs, and vanilla. Add carrot puree; mix to combine. With mixer on medium speed, slowly pour melted butter into carrot mixture until well combined.
Step 4: Pour carrot mixture into flour mixture and stir using a wooden spoon until just combined. Fold in grated carrots and nuts.
Step 5: Transfer batter to prepared pan. Bake cake for 40 to 45 minutes or until the center bounces back when lightly pressed and a cake tester inserted into the center comes out clean. Let cool for 10 minutes in the pan, then gently lift the cake from the pan using parchment. Discard paper; cool cake completely on a wire rack lined with parchment.
Step 6: While the cake cools, make buttercream: Place butter in a large bowl. Scrape seeds from the vanilla bean into the bowl. With a hand mixer, beat on medium speed until light and airy, 1 to 2 minutes, scraping down the side and bottom of the bowl as needed.
Step 7: Add sugars; mix on low speed to combine. Increase speed to medium for 30 seconds. Stop mixer, add cream. (Change to whisk attachment if you have one.) Beat on medium until combined, then beat on medium-high until airy, 1 to 2 minutes.
Step 8: Frost cooled cake with buttercream; sprinkle lightly with sea salt.

PREP TIME & NUTRITION:
Prep Time: 15 mins, Cook Time: 45 mins, Total Time: 1 hr, Servings: 12, Calories: 320, Net Carbs: 40g, Fats: 15g, Protein: 4g