Preheat the oven to 375 degrees F. Line a baking sheet with parchment paper.
Heat the olive oil in a small saute pan over medium-high heat until shimmering, 2 to 3 minutes. Add the garlic and sweat for 30 seconds, shaking the pan to move around the garlic until it starts to turn golden. Add the panko and toast until crisp
, stirring occasionally, 1 to 2 minutes. Season the panko with salt and pepper, toss with the parsley and let cool.
Gently mix together the Manchego, mashed potatoes and chorizo
and set aside. Stuff each pepper with 2 tablespoons of the mixture. Dip the opening of each pepper in panko, and then roll around in the panko
to lightly coat. Lay out the peppers on the prepared baking sheet and bake until warmed through and the panko is golden brown, about 25 minutes. Cool for 5 minutes and serve hot or at room temperature.