Preheat the oven to 400º F with a rack in the center. Line a rimmed baking sheet with foil. Lightly coat the cups of a 12-cup mini muffin tin with cooking spray, and set aside.
Combine 1-3/4 cups water, agar agar, celery, rosemary, bay leaf, peppercorns, allspice berries, parsley, and 1/4 teaspoon table salt in a small saucepan. Bring to a simmer over high heat, scraping bottom of pan occasionally, then reduce heat to low. Continue to scrape the bottom of the pan occasionally, as the agar agar likes to settle, until it appears dissolved, about 6-8 minutes.
Add peas to a blender and puree. Strain the agar agar broth through a fine-mesh strainer into blender. Add heavy cream, brie, a pinch or two of cayenne, and additional water to bring the volume just above 2 cups. Blend until smooth, scraping down the sides of the blender as needed. Taste and adjust seasoning with salt, white pepper, and additional cayenne if desired, blending briefly to fully incorporate. Evenly distribute the mixture among the 12 prepared muffin cups. Tap pan several times to settle and help remove any air bubbles that may have formed. Set aside for about an hour for the agar agar to set.
At serving time, run a thin knife around edge of panna cotta, then pop each out.
Using a 1-inch round cutter, cut circles of the prosciutto. Place on a sheet pan with parchment paper and bake 10–15 minutes until crisp. Reserve for garnish.
Combine all ingredients in a blender and mix until smooth and incorporated. Refrigerate.
Place the panna cotta on a tray, and dollop a small dollop of aioli on top of each. Place a prosciutto disc on the aioli. Top with a small drop of aioli on the prosciutto crisp. Garnish with micro greens or celery greens.
The panna cotta is best served warm or at room temperature. Do not reheat it in the microwave or it will melt. Remove from muffin tin just before serving. I always love the combination of sweet peas and salty prosciutto and the sensation of a savory custard.
This can be made with roasted garlic or broccolini panna cotta.
This is a great dish for a fall evening with a nice Pinot Grigio.