Preheat oven to 325°F Line 3 cookie sheets with parchment paper.
In a small glass bowl, put water & almond paste together & stir until mixed, set aside.
In a large mixing bowl, cream together butter & sugar until fluffy.
In the meantime; in a separate bowl, mix together flour, baking powder & salt.
Add water/paste mix, vanilla, & 8 eggs into the butter/sugar mixture, mix well.
Stir flour mixture into the butter mixture; mix well.
Fold in the unsweetened coconut & nuts.
Turn out unto a lightly floured surface & divide into 6 equal parts. Place each 1/6 of dough onto cookie sheets and form into logs about 14" long & 1 1/2" wide. (2 pcs per cookie sheet).
In Small bowl beat last egg & tablespoon water for wash. Brush top & sides of each log & sprinkle 1/3 cup of sweetened coconut on & pat very lightly.
Bake 25-30 minutes until very lightly browned. Cool COMPLETELY. Cut each log diagonally into 3/4" slices. Arrange on baking sheets (no paper) & continue baking for 11 minutes, flip (very gingerly) & bake for an additional 11 minutes. Remove & cool completely.
While cooling, line several baking pans with wax paper. Place chocolate & oil in pan over low heat, stirring until melted. Dip bottom sides of biscotti into chocolate and lay on their sides onto wax paper until set. I find putting full baking sheets into freezer for 5 minutes, really makes a nice smooth set.