Peel and finely dice the shallots and garlic.

In a small saucepan, combine the diced shallots, garlic, thyme leaves, a pinch of salt, port, and cider brandy. Bring to a simmer over the fire.

While the liquid simmers, trim the chicken livers.

Heat a pan over hot coals. Add the chicken livers, season with salt, and sauté quickly. Deglaze with a splash of brandy and cook until just browned but still pink inside.

Transfer the cooked chicken livers and the simmered aromatic mixture to a food processor and blend until combined.

Melt the butter. While the food processor is running, add the eggs one by one, then slowly pour in the melted butter until the mixture is smooth.

Strain the mixture through a fine-mesh sieve into a bowl. Season with fine salt and ground white pepper, then stir to combine.

Line a terrine mold with plastic wrap. Pour the strained parfait mixture into the mold and cover with another layer of plastic wrap.

Place the terrine in a larger baking dish. Create a water bath by pouring hot water into the larger dish around the terrine. Bake in the oven until set.

After baking, let the parfait cool. Pour a layer of melted butter over the top to seal it, then chill in the refrigerator until firm.

Toast slices of bread until golden brown.

Unmold the chilled parfait, slice, and spread generously on the warm toast. Top with jam if desired and serve.