Healthy Chocolate Walnut Cake

8 eggs
1 c sugar, divided
1/2 c brown sugar
1 1/2 c toasted ground walnuts
2 t vanilla
6 T flour
1/3 c cocoa
1/2 t salt
1/4 t cinnamon
3/4 c fruit jam
1 t powdered sugar

Preheat oven to 375. Lightly oil & flour 9-in spring form pan.
Crack 2 eggs into large bowl. Separate 2 more eggs, placing whites in 2nd large bowl, & yolks in 1st bowl. Separate remaining 4 eggs, adding whites to 2nd bowl (yolks not needed).
Beat egg whites on high til foamy. Add 1/3 c sugar, & beat til soft peaks form. Set aside.
Add brown sugar & remaining 2/3 c sugar to 1st bowl, & beat on medium speed til thick & light brown. Beat in nuts & vanilla. Beat in flour, cocoa, salt, & cinnamon. With rubber spatula, fold in 1 c beaten egg whites, til smooth. Fold in remaining egg whites very gently (some white streaks may be visible). Gently pour into pan.
Place pan in oven & reduce heat to 325. Bake til set, 40-45 mins. Cool completely on wire rack.
Remove pan's side. Release cake from pan's bottom with long, thin, metal spatula, & transfer to serving plate. Slice cake in 1/2 horizontally with long, thin knife. Lift off top, spread jam over bottom layer, & replace top. Sprinkle with powdered sugar.