Preheat
the oven to 350°F/180°C/gas 4. Butter a
9-inch (23-cm) baking pan.
Almond-Toffee
Topping; Melt the butter with the granulated
and brown sugars in a small saucepan over
low heat.
Add the milk and bring to a
boil, stirring constantly. Remove from the
heat and stir in the almonds.
Cookie Base:
Sift the flour, baking powder, and salt into
a medium bowl. Beat the butter and sugar
in a large bowl with an electric mixer at
high speed until creamy.
Add the egg,
beating until just blended. Mix in the dry
ingredients and lemon zest.
Firmly press
the mixture into the prepared pan to form a
smooth, even layer. Spread the
almond-toffee topping evenly over the cookie
base.
Bake for
30-35
minutes,
or until just golden. Cut into bars while
the topping is still warm.