Question: Who owns a company that manufactures frozen dessert machines, like soft serve machines, shake machines, slush machines, and batch freezers that is most known for being the soft serve machine used by a chain of soft serve ice cream and fast-food restaurants owned by International Dairy Queen, Inc?

Context paragraphs:
Storm (ice cream): Sold at Hungry Jack's fast food restaurants, a Storm is a flavoured ice cream dessert similar to McDonald's McFlurry ice cream.  The product consists of vanilla flavoured soft serve ice cream served with either one of three flavours; Cookies & Cream (Oreo), Flake or Rainbow (Sprinkles).  The selected flavour is then whipped together with the ice cream using a blender.

Carvel (restaurant): Carvel is an ice cream franchise owned by Focus Brands.  Carvel is best known for their soft serve ice cream and ice cream cakes, which feature a layer of distinctive 'crunchies'.  It also sells a variety of novelty ice cream bars and ice cream sandwiches.

Soft serve: Soft serve is a type of ice cream that is softer than regular ice creams as a result of air being introduced during freezing.  Soft serve ice cream has been sold commercially since the late 1930s.

Dairy Queen: Dairy Queen, often abbreviated DQ, is a chain of soft serve ice cream and fast-food restaurants owned by International Dairy Queen, Inc., a subsidiary of Berkshire Hathaway.  International Dairy Queen, Inc., also owns Orange Julius and Karmelkorn.

Ice cream parlor: Ice cream parlors (or parlours) are restaurants that sell ice cream, gelato, sorbet, and frozen yogurt to consumers.  Ice cream is typically sold as regular ice cream (also called hard-packed ice cream), gelato, and soft serve, which is usually dispensed by a machine with a limited number of flavors (e.g., chocolate, vanilla, and "twist", a mix of the two).  It is customary for ice cream parlors to offer a number of flavors and items.  Parlors often serve ice cream and other frozen desserts in cones or in dishes, to be eaten with a spoon.  Some ice cream parlours prepare ice cream desserts such as sundaes (ice cream topped with syrup, whipped cream and other toppings) or milkshakes.

List of frozen yogurt companies: This is a list of notable frozen yogurt companies.  Frozen yogurt is a frozen dessert made with yogurt and sometimes other dairy products.  It varies from slightly to much more tart than ice cream, as well as being lower in fat (due to the use of milk instead of cream).  It is different from ice milk (more recently termed low-fat or light ice cream) and conventional soft serve.  Unlike yogurt, frozen yogurt is not regulated by the U.S. Food and Drug Administration (FDA), but is regulated by some U.S. states.  Frozen yogurt may or may not contain live and active bacteria cultures.

List of ice cream parlor chains: This is a list of notable ice cream parlor chains.  Ice cream parlors are places that sell ice cream, gelato, sorbet and frozen yogurt to consumers.  Ice cream is typically sold as regular ice cream (also called hard-packed ice cream), gelato and soft serve, which is typically dispensed by a machine with a limited number of flavors (e.g. chocolate, vanilla, and a mix of the two).  It is customary for ice cream parlors to offer several ice cream flavors and items.

Dairy mix: A dairy mix is the blend of milk, cream, sugar, stabilizers, and vanilla packaged by a dairy for commercial use.  This mix can either be made directly into ice cream or placed into containers for the use in soft serve, frozen custard, or ice cream machines.  Dairy mix used in restaurants can be also used to make frozen drinks or smoothies.

Frozen yogurt: Frozen yogurt (also spelled frozen yoghurt; also known as frogurt or by the tradename Froyo ) is a frozen dessert made with yogurt and sometimes other dairy products.  It is usually more tart than ice cream, as well as lower in fat (due to the use of milk instead of cream).  It is different from ice milk (more recently termed low-fat or light ice cream) and conventional soft serve.  Unlike yogurt, frozen yogurt is not regulated by the U.S. Food and Drug Administration (FDA) but is regulated by some U.S. states.  Frozen yogurt may or may not contain live and active bacteria cultures.

Electro Freeze: Electro Freeze is a company that manufactures frozen dessert machines, like soft serve machines, shake machines, slush machines, batch freezers, etc., and is owned by H C Duke & Son.  It is most known for being the soft serve machine used by Dairy Queen, as well as many other Soft Serve Ice Cream establishments.

Supporting paragraphs: Electro Freeze Dairy Queen
Answer: H C Duke & Son