This turns out to be a really interesting question. 

Halwa, as it is found in South Asia, is a a pudding-like mixture made in its most basic form from a combination of: 

• ghee

• sugar or jaggery

• some form of flour (or lentils, or noodles, or starchy vegetables)

Halwa is cooked over a stove top until thick and creamy, and eaten with a spoon.

Halwa is in the same class as, but very different from, Halvah or Halva or Helva or Helava!) which is Persian or Arabic in origin and simply means a sweet, semisolid fudge that can be made from practically anything but traditionally has sesame as a dominant flavour. In Greece and Turkey, halvah is usually made from semolina and honey. 

You can make cherry paste by soaking the cherries for 1 to 2 hours or until quite soft. Strain and reserve the liquid. Transfer cherries to a high-speed blender and process until smooth. Add some of the reserved liquid back to achieve the consistency you need.

Alternatively, you can buy cherry paste here, but it's not cheap. 

What is linseed?

Linseed is a small seed, typically reddish-brown or golden-yellow. It comes from the common flax plant and is also known as flaxseed.

Linseeds add marked dietary fibre to the diet, so be careful in the quantity added to food. This seed is a laxative.

Culinary grade linseed oil has a rich, buttery taste and is useful to add richness to dishes.

How to cook linseeds

Whole or ground linseeds do not need to be cooked and can be added to almost any dish, including breads, biscuits and cakes, snack bars, and even to curries and vegetable stews. 

Linseed and flaxseed oils should never be used for cooking as they have a very low flash point and can easily burst into flame. Instead, mix linseed oil with other oils in dressings for salads and vegetables.

Linseeds are also a great binder, and work really well as an egg replacer in lots of recipes. Add 1 tbsp milled linseed to 2 tbsp water and leave to swell before adding to cakes and biscuits to bind ingredients together as an egg would.