Preheat your oven to 350°F (175°C). Start by browning the butter for the streusel.
In a small pan over medium heat, melt the butter, stirring occasionally. Once it foams and subsides, you’ll be left with a golden, nutty-smelling butter. Transfer it to a bowl and refrigerate while you prepare the batter.
In a large bowl, whisk together olive oil, brown sugar, eggs, pumpkin purée, Greek yogurt, and vanilla extract until smooth. Add the dry ingredients—flour, pumpkin pie spice, baking soda, baking powder, and salt—and stir until just combined.
Line a 9"x5" loaf pan with parchment paper and pour the batter in.
For the streusel, take the cooled brown butter and mix it with flour, brown sugar, and pumpkin pie spice. Use your hands or a mixer to combine until the mixture holds together but crumbles easily. Sprinkle the streusel evenly over the batter.
Bake for 45-50 minutes, or until a toothpick inserted in the center comes out clean.
While the loaf cools, make the glaze by whisking powdered sugar and maple syrup together until smooth. Drizzle over the cooled loaf or individual slices. Enjoy!