Fat. It's one of the few three-letter four-letter words, and Jennifer McLagan wants you to embrace it. In all its many, wondrous and tasty forms, fat is the subject and title of Jennifer's recent cookbook. But it's the subtitle that makes it clear where she's coming from: "An Appreciation of a Misunderstood Ingredient, with Recipes." The book, equal parts science, history and cooking, is divided into four simple chapters - butter, pork fat, poultry fat, and beef and lamb fats.

It's been called controversial, but Jennifer believes that it's the 'bad' fats - polyunsaturated and synthetic fats - that are making us unhealthy. She feels that the animal fats that we've been eating for centuries are the best for us, plus they add flavour! On the show, she and Steven made Prosciutto-Wrapped Halibut with Sage Butter along with Duck Fat and Grapefruit Salad Dressing.

Prosciutto-Wrapped Halibut with Sage Butter

"Fish and seafood are often paired with bacon, which imparts both flavour and fat. In this recipe, I use prosciutto because it turns very crisp and crunchy, providing a good contrast to the fish. You could simply drizzle the cooked fish with some melted butter, but I like to use a brown butter and sage sauce for another layer of flavour. This is a great dinner party dish. The fish, which can be prepped in advance, look very impressive in their prosciutto belts. Halibut, cod, or any other firm white fish works well in this recipe. Serve with a simple green vegetable and steamed potatoes."

Serves 6

Six 6-ounce/175 –g skinless halibut fillets
Sea salt and freshly ground black pepper
36 fresh sage leaves
6 slices prosciutto
2 large lemons
7 tablespoons/3 1/2 ounces/100 g unsalted butter

Preheat the over to 400°F/200°C.

Season the fish fillets with salt and pepper. Place 2 sage leaves on top of each fillet and then wrap each with a slice of prosciutto. The prosciutto will form a belt, enclosing the leaves but leaving the fish exposed at either end. Cut 12 slices 1/4 inch/6mm thick from the center of the lemons, reserving the end for their juice.

On a rimmed baking sheet, arrange pairs of the lemon slice, slightly overlapping. Place a wrapped filled on top of each pair of lemon slices. Bake the fish until it flakes and is opaque at the thickest part, 15 to 20 minutes, depending on the thickness of the fish.

While the fish is cooking, melt the butter in a frying pan over medium-low heat. Add the remaining 24 sage leaves and cook, turning once, until the leaves are crisp and the butter begins to brown, about 7 minutes. Remove from the heat and add salt and the juice from the remaining lemon ends.

Transfer the fish and the lemon slices to warmed plates. Pour any juices released from the fish into the sage butter sauce and pour the sauce over the fish. Serve immediately.

TIP: Make sure all your fish fillets are a similar size and thickness so they will all be cooked through at the same time.

Duck Fat and Grapefruit Salad Dressing

"This is my friend Colin's recipe. One evening when he came over for dinner he brought his own salad and dressing. I was a bit miffed, until I tasted it. The combination of grapefruit and hot duck fat sharpened with vinegar was wonderful. Colin poured it over a bowl of shredded napa cabbage, and I've since made this dressing with foie gras and goose fat and poured it over everything from spinach to dandelion greens. If you have any duck cracklings, they make an excellent addition to this salad."

Serves 4

2 grapefruit
6 cups/300 g shredded napa cabbage
1/4 cup/ 1 3/4 ounces / 50 g duck fat
1 tablespoon finely chopped shallot
1 tablespoon sherry vinegar
Sea salt and freshly ground black pepper

Finely grate 2 teaspoons of zest from 1 grapefruit and set aside. Cut a thick slice off the top and bottom of both grapefruit to expose the flesh. Stand the fruit on a cutting board and cut away both the skin and the pith. Holding the fruit over a bowl, cut along either side of each segment to the center to free it from the membranes. Squeeze the juice from the spend membranes. Measure 1/4 cup/60ml of the juice, pour into a bowl, add the grapefruit segments, and set aside.

Place the shredded cabbage in a serving bowl.

Heat 1 tablespoon of the duck fat in a small frying pan over medium heat. Add the shallot and cook until softened and just beginning to colour. Add the remaining duck fat and the grapefruit segments and juice to the pan.

Pour the hot dressing over the shredded cabbage and toss to mix. Serve immediately.