Sift whole wheat flour and baking powder together.
In a bowl, mix whole wheat flour, salt, and sugar.
Add cold butter and blend until the mixture resembles breadcrumbs.
Add cold water, knead into a dough, and refrigerate to rest.
Roughly chop the walnuts.
In a bowl, mix eggs, brown sugar, honey, and butter together.
Add the walnuts to complete the filling.
Evenly spread the dough in a pie pan.
Pour the walnut filling into the pan.
Bake in a preheated oven at 180°C (356°F) for 30-35 minutes.