Preheat the oven to 350°F / 175°C. Line a muffin tin with 6 parchment liners.
To a medium sized mixing bowl, add the flour, pistachio flour, baking powder, salt, sugar, and cubed butter. Use a hand mixer or a stand mixer fitted with the paddle attachment to beat the mixture together until the butter has completely combined with the dry ingredients and no lumps remain.
Add in the oil, egg white, vanilla bean paste, sour cream, and milk. Whisk the ingredients together just until a cohesive batter has formed.
Distribute the batter evenly between the six liners. Bake for 15-18 min., or until a toothpick inserted in the center of the cupcakes comes out with only a few moist crumbs.
Raspberry Jam
Set a fine mesh sieve over a small bowl. Set aside.
Add the raspberries, sugar, and lemon zest to a small saucepan set over medium heat. Stir the mixture frequently, mashing down the raspberries as they soften.
Once all the raspberries have been mashed up, take the mixture off of the heat and pour it through the fine mesh sieve.
Discard the raspberry seeds, and transfer the mixture back into the saucepan and bring it to a simmer.
In a small bowl, mix together the corn starch and lemon juice. Once the raspberry mixture is simmering, mix the corn starch slurry in to it, stirring until the jam thickens.
Once thickened, remove the jam from the heat and transfer it to a heat-safe container to chill in the fridge until you're ready to assemble the cupcakes.
Mascarpone Whipped Cream
Add the mascarpone, sugar, and vanilla to a medium sized mixing bowl. Use a hand mixer (or a stand mixer fitted with the whisk attachment) to beat the mixture just until combined.
While mixing, slowly pour in the heavy whipping cream. Continue mixing until the mixture reaches stiff peaks.
Once the cupcakes have fully cooled to room temperature, place a heaping scoop of mascarpone frosting on them. Use a spoon to make a divot on top of the cream, then swirl a heaping scoop of raspberry jam in to it. Enjoy!