Add the whole shrimp (shells, heads, tails and all), broth, Dijon mustard, onion powder and tomato paste to a large saucepan. Stir, bring to a boil over medium-high heat, then turn the heat down and simmer for 5 minutes, until the shrimp are pink and cooked through.

Let the mixture cool for a few minutes, then carefully transfer it to a countertop blender and blend until as smooth as possible (vent the lid and cover it with a towel, since the liquid is hot). You can also blend it right in the pan with an immersion blender; keep going for 2 to 3 minutes so the shells break down well.

Set a fine mesh sieve over a clean saucepan and press the mixture through it with the back of a ladle or spoon, scraping the underside of the sieve so you get every drop. Discard the shell pieces left in the sieve.

Stir in the heavy cream and the brandy (if using). Taste, season with salt and pepper, and warm gently over low heat without letting it boil.

Meanwhile, melt the butter in a small skillet over medium-high heat and fry the two garnish shrimp for 1 to 2 minutes per side, until pink.

Ladle the bisque into two bowls, swirl in a little extra cream, and top each bowl with a shrimp. Serve hot.