*Note: Make your peach-basil curd at least 4 hours in advance, so it has time to chill and thicken in the fridge*
For your curd, place your chopped peaches into a deep bowl and with your immersion blender, pulverize them into a sauce-like consistency. Add your brown sugar, egg, egg yolk, lemon juice, and salt to the bowl and whisk together.
Pour your curd mixture into a pot and place over medium heat, whisking continuously for 5-7 minutes, until thickened. Keep your temperature consistent; you don’t want to boil your mixture and risk it curdling. Your curd is done once it reaches between 170°F - 175°F
Once your curd has thickened, remove from the heat and tear in your 2-3 leaves of fresh basil. Stir and leave to sit for 10 minutes.
Place your cubed butter into a heat-safe bowl or pitcher and place a fine mesh sieve over top. Pour your curd through the sieve, using a spatula or spoon to press the mixture through. Whisk the butter and the peach mixture together. Discard the pulp/leaves left in the strainer.
Allow your curd to cool at room temperature for 10 minutes, then cover and place in the fridge to chill completely.
Preheat oven to 350°F. Flip your muffin pan over, so the cups are sticking up, and grease four of the cups
Lightly flour your counter and unfold your puff pastry dough onto it. Give it a light roll with a rolling pin, then use your 4-inch cutter to cut out 4 round shapes.
Mold your shapes over the top of each greased muffin cup, gently pressing to shape along the mold
In a bowl, beat your egg with a splash of milk or water. Brush your egg wash all over the exposed dough on the muffin cup. Cover your pan with parchment paper and a baking sheet
Place in the oven on the middle rack and bake for 12 minutes. Remove the baking sheet and parchment paper and bake for an additional 5 minutes
Remove from the oven and allow the pastry to cool on the pan for 5 minutes before gently removing each shell and placing on a wire rack to cool completely
Slice your remaining peach and add it to a bowl with your brown sugar, salt, and chopped basil. Stir and leave to sit for at least 5 minutes. This will amplify the peach flavor and bring out some extra juices
In a medium bowl, add your heavy cream and sift in your powdered sugar. Whisk until you have medium-soft peaks (aka the whipped cream holds its shape without running right off the whisk)
To assemble your peach-basil tarts, divide your chilled peach curd evenly among the four puff pastry cups. Top with whipped cream and some of your macerated peaches. Sprinkle with extra brown sugar and enjoy!