Heat the oven to 400°F. Line a baking sheet with parchment paper.
In a large bowl, whisk together the flour, brown sugar, pumpkin pie spice, baking powder, baking soda, and salt. Cut the butter into small pieces and blend into the flour mixture with a pastry blender or two knives. You want both pea-sized and larger chunks of butter, so don't over-blend.
In a separate bowl mix together the pumpkin, 1/2 cup cream, and vanilla until smooth. Add to the flour mixture and stir until the dough comes together with no loose dry bits.
Transfer to parchment-covered pan and pat the dough into a circle about 1/2 inch tall. Cut scones into 8 wedges. Leave in a circle or separate as desired.
Bake scones for 15-18 minutes, until golden. Transfer to a wire rack to cool.
To make the ganache topping, add the white chocolate chips to a microwave-safe bowl. Microwave at 50% power for 1 minute, then remove and stir. Return to the microwave and heat in 30 second increments at 50% power until just about melted. Stir to melt completely, then stir in the cream until smooth. Drizzle or spread over cooled scones.
Serve immediately or let ganache set before serving.
Notes
Store in an airtight container at room temperature for up to 3 days.
Nutrition estimate reflects using all of the ganache; if you are drizzling you will have some left over.