Hi Martin. "Bisquick" is a commonly-used biscuit mix in the US. Here are three copycat recipes for Bisquick. Enjoy!

BIS-QUICK-AS-A-WINK
Source: Gloria Pitzer, The Recipe Detective
Makes about 10 cups

8 cups flour
1 1/4 cups nonfat dry milk powder
1/4 cup baking powder
1 tablespoon salt
2 cups shortening

Combine flour, milk, baking powder, and salt in a very large bowl. Cut in shortening until it resembles coarse cornmeal. Store in tightly closed covered container in a cool place.

BISCUIT MIX
Source: Pure and Simple by Marion Burrows
Makes: 13 cups

9 cups flour; sifted (cake & pastry flour preferred)
1 cup plus 2 tbsp powdered milk
1/3 cup baking powder
4 tsp salt
1 3/4 cups vegetable shortening

Sift all dry ingredients. Cut shortening into flour mixture till mixture resembles coarse cornmeal. Store, well covered, in cool, dry place.

Use for pancakes, waffles, biscuits or anything that you would use packaged biscuit mix.

SUBSTITUTE BISQUICK

5 cups flour
2 1/2 tbsp baking powder, double acting
2 tbsp sugar
2 tsp salt
1 tsp cream of tartar
1 cup shortening

Sift dry ingredients together. Cut in shortening with pastry blender until it resembles crumbs. Store in airtight container up to six weeks at room temperature, or freeze for up to six months.