Maple Shortbread Bars

"Nut allergies are an awful affliction. I fully sympathise with nuts avoiders as I do with anyone who genuinely needs to deprive themselves of the pleasures a food group. The bars below are sadly not for the allergics: they are a nutter’s paradise and a take on the original pecan pie bars from NY Times Cooking. I like nuts but pecans and walnuts are probably my least favourites so I replaced them with what I like best: almonds and pistachios. Feel free to return to pecans though, by all means."