Special equipment: 2 (18 1/2-inch or 10 1/2-inch) foil pans; Pastry brush
Preheat the oven to 350 degrees F.
Put the Chardonnay, water, lemon, peppercorns, juniper berries, bay leaves, basil and 2 fennel fronds into a large saucepan. Place the pan over high heat and bring the liquid to a boil. Reduce the heat to low and let the liquid simmer for 10 minutes. Remove from the heat, discard the fennel and basil and let cool.
Put the salmon into the foil pan and top with the remaining fennel frond. Pour the poaching liquid over the salmon. Cover the pan with foil and seal it tightly. Place the pan into the preheated oven for 20 minutes. Remove the foil halfway through the cooking process and baste the salmon. Reseal and finish poaching. Remove the pan from the oven, remove the foil and brush the top of the salmon with the poaching liquid to remove any white bits.
When the pan is cool enough to handle place it over your sink. With a sharp knife, make a few punctures in the bottom of the pan to let the poaching liquid drain. Place the pan directly into the second pan to prevent dripping. Brush the salmon with olive oil, cover with foil and refrigerate overnight.
To serve, cut the end off the foil pan and, with a spatula, slide the salmon onto a platter. Fan the lemon slices out along the top and garnish the sides with the dill. Serve with Dill Dijon whipped cream on the side.
Pour the heavy cream into a large bowl and, using an electric mixer on high, beat until soft peaks form. Add the mustard and continue to beat on medium for 1 minute. Fold in the dill and season with salt and pepper, to taste.
Transfer to a decorative bowl for serving.