Marble Shortbread II

My second homemade cookies.... The first shortbread version I made uses almond powder and I wanted to make another version without it and found this one. I think the one with almond tastes better & crispier too.

Source: Forum (by Anasue) - recipe modified to fit 12" sq tin
Makes 12" x 12" --> 100 pieces
INGREDIENTS:
380g Butter
160g Caster Sugar
400g Flour
75g Rice Flour
1/2 tsp Salt

TOPPING:
280g Cooking Chocolate*
1.5 tbs Veg Shortening* (* melt & mix) 
90g White Chocolate

METHOD:
1. Cream butter & sugar until fluffy.
Add in flour & salt.

2. Grease tin & cutter.
Spread & press the dough into the tin.
Prick the surface with fork.
Place the cutter on top of the batter & press in.

3. Bake 180C for 20 minutes.
Rest for 10 min before removing the cutter.
Cool completely.

4. Spread melted chocolate on top of the shortbread.
Drizzle with white chocolate & create marble pattern.
Replace cutter & chill for 20 minutes until the chocolate set.
Remove cutter & keep shortbread in an air tight container.