Preheat oven to 350 degrees. Lightly butter and flour a 4 1/2-by-8 1/2-inch loaf pan. In a large bowl, using an electric mixer, beat butter and both sugars on medium-high until very light and fluffy, 7 minutes. Scrape down bowl and beat 1 minute more. Add maple syrup, then gradually add eggs, beating well and scraping down bowl as needed. With mixer on low, add salt, then gradually add flour, beating well to combine and scraping down bowl as needed. Fold pecans into batter.
Transfer batter to pan and bake until a toothpick inserted in center of cake comes out with a few moist crumbs attached, 65 minutes. Let cool in pan on a wire rack, 1 hour. Remove cake from pan and let cool completely on rack before slicing.
Let refrigerated butter sit at room temperature for 30 minutes; it should hold an indentation when pressed. If your eggs are cold, submerge them in warm water for 15 minutes.