Add apple cider to a heavy bottomed 4QT Saucepan or 3QT Saucier and bring to a boil over medium heat. Reduce to a simmer and cook, stirring occasionally and watching closely, until the cider has reduced to about ⅓ cup, 30–40 minutes. The cider should be thick and syrupy. (The wider your saucepan, the quicker this process will go!)

Once the cider has reduced, add granulated and light brown sugar, butter, corn syrup, and heavy cream. Stir everything together until melted and homogenous, then cease stirring.

Attach candy thermometer (if using) to the side of the pan and bring the mixture to a rolling boil over medium-high heat without stirring (only swirling). Bring mixture to 252F, or soft-ball stage (if not using a candy thermometer). This should only take about five minutes at a rolling boil. To test for soft-ball stage: drop a bit of the hot caramel into a bowl of very cold water. The caramel should form a—you guessed it—soft ball.  When removed from the water it should resemble a soft, squishy ball that holds its shape for a second before warming from the heat of your hands.

Immediately remove from heat and stir in cinnamon, salt, cardamom, vinegar, allspice, ginger, and vanilla. Keep warm.

Preheat oven to 325F.

Mix together the flour, milk powder, cinnamon, baking powder, and salt in a medium bowl, set aside. This is the dry mixture.

In a Butter Warmer set over medium heat, melt the butter and white chocolate together, stirring until fully combined.

Add the brown sugar, eggs, and vanilla to a large bowl. Whisk together until all is combined and the sugars are hydrated (it will be a little thick at this point.) Whisk vigorously until the mixture has lightened by a shade or two and increased in volume, about 2 minutes.

Stream in melted white chocolate mixture and whisk until homogenous.

Swap the whisk for a spatula and stir in the dry mixture until fully combined; do not overmix.

Spread blondie batter evenly into an 8x8" Baking Dish with the back of a spoon.

Working quickly, drizzle about half (1 cup) of the still-warm caramel over the surface of your blondies. You want to leave a few peeks of the blondies underneath, not fully cover the top – don’t worry if it looks a little messy, that’s the point!

Using a spoon or butter knife, swirl the apple cider caramel into the surface of the blondies until some caramel has combined with the batter, but there are still gorgeous pools of caramel left.

Bake until the blondies have puffed and then settled, the top is golden brown, and the pools of caramel are bubbling away,  40–50 minutes.

Cool for at least an hour before digging in. For a chewier blondie, store these wrapped in the fridge for up to 7 days. Otherwise, store at room temp well wrapped for 2–3 days.