Those Nanaimo Bars look interesting, although I'm generally opposed to most things using instant pudding. In the interest of research I looked them up and came across these alternative fillings, incase you want to be fancy when you make them next. They're still Canadian, I got them off some canadian website.

VARIATION: Peanut Butter Filling
2 T Custard powder
1/4 c Milk
2 Tbsp Butter; softened
1/2 c Peanut butter, smooth
2 c Sugar icing sugar or confectioners -sifted
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VARIATION: Grand Marnier Filling
2 c Icing Sugar
1/4 c Butter; softened
1/4 c Grand Marnier or orange -liqueur
1 tb Orange rind; coarsely grated
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VARIATION: Cherry Filling
1/4 c Butter; softened
1 Tbsp. Cherry juice
2 c Icing sugar
1/3 c Maraschino cherries; chopped
drop or 2 of red food coloring
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VARIATION: Mint Filling
1/3 cup butter
3 Tbsp custard powder, Bird's brand
(or substitute jello pudding powder)
1/4 cup milk
3 cups icing sugar
1 tsp. peppermint flavoring
1 or 2 drops green food coloring as desired.
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VARIATION: Cappuccino Filling
2 Tbsp milk
3 Tbsp unsalted butter
2 tsp instant coffee or espresso powder
1/2 tsp vanilla
2 cups icing sugar (aka powdered or confectioners)
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VARIATION: Bailey's Irish Cream
1/3 cup butter
3 Tbsp custard powder, Bird's brand
(or substitute vanilla jello pudding powder)
1/4 cup Bailey's Irish Cream
2 - 3 cups icing sugar