1. Pre-heat oven to 325 F. Butter 8-inch round cake pan and line base with parchment paper.
2. Gently toss berries with lemon juice and Raspberry, Natural Flavor Blend; set aside.
3. In large bowl, whisk together sugar, eggs until pale and thick. Carefully fold in flour, baking powder and lemon zest. Gently stir in melted butter.
4. Pour batter into pan, then scatter in raspberries and their juice. Sprinkle a little sugar over top. Bake for 1 hour, or until the cake springs back to touch. Check torta halfway through cooking time; cover with foil if you need to prevent top from scorching. Its done when evenly colored, springy to the touch, pulling away slightly from the pan and tooth pick inserted into center comes out clean.
5. Allow to cool completely in the pan before serving. Cut into wedges. Can be topped with whipped cream or ice cream if desired.