Topping - Combine all ingredients in a small bowl and set aside.
Batter - Mix oil, sugar, vanilla, and eggs in a large bowl. Add mashed banana and stir until combined. Add flour, baking soda, baking powder, and salt. Stir until just combined. Do not beat. Add 3/4 cup of white chocolate chips and stir until combined.
Pour into prepared pan. Top with remaining 1/4 cup of white chocolate chips and cover with streusel topping.
Bake in center of preheated oven for 65-75 minutes or until toothpick inserted in center of loaf comes out clean. Cool in pan on rack.