Preheat the oven to 350 degrees F (175 degrees F). Grease and flour a 9x5-inch loaf pan.

In a medium bowl, combine dates and butter. Pour boiling water over top and let stand until cool.

Stir cooled date mixture to break up any clumps. Add brown sugar and egg; mix until well blended.

Combine flour, baking soda, baking powder, and salt in a bowl. Stir flour mixture into date mixture until just blended. Stir in walnuts. Pour batter into the prepared pan.

Bake in the preheated oven until a wooden pick inserted into the center comes out clean, about 50 minutes.