Blondie Sundaes With Fried Walnuts and Candied Fennel

Preheat oven to 325 °F. Lightly coat a 13x9" baking dish with nonstick spray. Whisk buckwheat flour, almond flour, and salt in a medium bowl to combine. Cook butter in a medium saucepan over medium-low heat, stirring often, until it foams, then browns, 5 –8 minutes. Transfer to a large bowl; let cool slightly. Add sugar and whisk until smooth. Whisking constantly, add egg yolks one at a time followed by whole egg, beating after each addition to fully incorporate before adding more. Add dry ingredients and mix until smooth. Scrape batter into prepared dish; smooth top. Bake blondies until lightly browned and center is firm when gently pressed, 15 –20 minutes. Transfer dish to a wire rack and let cool. Cut into 16 bars.