Preheat oven to 325 degrees. Sift flour, sugar, baking powder, and salt into a bowl. Mix in brown sugar. Make a well and add oil, egg yolks, water, maple flavoring. Beat with spoon until smooth. Beat egg whites and cream of tartar in large mixing bowl until whites form very stiff peaks, or 3–5 minutes with electric mixer on high speed. Do not under-beat. Pour egg-yolk mixture slowly over beaten egg whites, folding just until blended. Carefully fold in pecans. Pour into ungreased 9-inch square tube pan or 10-inch round tube pan. Bake at 325 degrees for 55 minutes, then increase to 350 degrees and bake 10–15 minutes longer, or until top springs back when lightly touched. Turn upside down over neck of funnel or bottle until cool. Loosen from sides with spatula. Hit edge sharply on table to loosen.