Make the yeast starter: stir the active dry yeast into the lukewarm water with 1 teaspoon of the sugar and let sit 5–10 minutes until foamy.
Combine dry batter ingredients: in a large bowl, stir together 3 cups sifted flour and 1/4 teaspoon salt.
Mix wet batter ingredients: in a medium bowl, whisk the yeast mixture with the 3 egg yolks, 1 egg white, and the remaining sugar; then add the remaining water, 1 1/2 cups milk, melted cooled butter, 2 teaspoons vegetable oil, vanilla, and almond extract until smooth.
Combine and aerate: stir the wet mixture into the flour until smooth, then beat remaining 3 egg whites in a clean bowl until stiff peaks form and gently fold them into the batter.
Let the batter rest: cover and let stand 1 hour, stirring every 15 minutes.
Preheat and cook waffles: preheat a Belgian waffle maker to medium, scoop batter onto the iron, spread if needed, close and cook until done per your waffle maker's indicator.
Prepare dredge and dip station: in a medium bowl combine 3 cups flour, 1 1/2 teaspoons black pepper, 2 teaspoons seasoned salt, and 1 teaspoon salt; pour 3 cups buttermilk into a shallow 8x8-inch dish.
Coat the chicken: pat chicken tenders dry, dredge each in the seasoned flour, shake off excess, dip in buttermilk, then dredge again in the flour and place on a wire rack; let rest 5 minutes to set the crust.
Heat oil and fry: heat vegetable oil in a deep pot or fryer to 350°F. Fry a few tenders at a time for 5–6 minutes until golden brown, turning if necessary about halfway. Transfer to a wire rack to drain.
Make sweetened butter: in a small saucepan over low heat gently melt 4 ounces butter and stir in 1 tablespoon powdered sugar until combined and warm.
Assemble and serve: place a waffle on a plate, top with 4 chicken tenders, dust with powdered sugar, and serve with the warm sweetened butter.
