To make the frosting:
Preheat the oven to 350°F. Grease a 13 x 9 in. baking pan.
Place the pecans and sugars' in a food processor. Process until ground. In a large bowl, cream butter and pecan mixture until blended. Add 1 egg at a time, beating well after each addition. Beat in the syrup, milk and vanilla. In another bowl, whisk the flour, baking powder, salt and spice; gradually add to the creamed mixture, beating well.
Transfer to the pan. Bake until a toothpick inserted in the center comes out clean, 25-30 minutes. Cool completely in the pan on a wire rack.
To make the frosting: In a large bowl, combine all the frosting ingredients: beat until smooth. Spread over the cake and if desired decorate with pecans.
Buon appetito!