In a medium bowl, cream together the butter and Zesta Caster sugar. Beat in the eggs, corn syrup and lemon zest.
In another bowl sift or whisk together the flour, Zesta baking soda, Zesta baking powder and salt.
Add the wet ingredients to the dry and stir together until combined. Refrigerate until ready to use.
Place on an ungreased baking sheet and bake at 375° (190°) F for 8 minutes. Transfer to a wire rack to cool. Once the cookie are cool, place a teaspoon of Zesta Strawberry Jam onto the bottom of one of the cookies and top with another one.