Preheat the oven
to 375°F/190°C/gas 5. Line two cookie sheets with
parchment paper.
Sift the flour
and baking powder into a large bowl. Beat the
butter, shortening, and brown sugar in a large bowl
with an electric mixer at high speed until creamy.
Add the vanilla
and egg, beating until just blended. Mix in the dry
ingredients and peanuts.
Drop teaspoons of
the dough 2 inches (5 cm) apart onto the prepared
cookie sheets.
Bake for
8-10
minutes,
or until firm to the touch. Transfer to racks to
cool.