In the U.S., a biscuit is something very simple, light, and convenient. It is unlikely have a lot of sugar or be covered with chocolate. However, there are no rules. You can make anything you want and call it a day "biscuit" if you like. To me, a "biscuit cookie" appears to be an oxymoron. If it's a cookie then it's a sweet. If it's a biscuit, then it's not. My interpretation of a "biscuit cookie" would be something that is both sweet and convenient (because it is small and light).

We don't really use the two words together in the UK - maybe sometimes it happens in USA. I don't think it changes the meaning. Maybe they are targeting USA primarily so want to say Cookie but are concerned about people interpreting it how a Brit would (we say Cookie in the UK but it refers to a certain type of biscuit - not the type depicted here) so to avoid misunderstandings they use both words. Or maybe they are using both words to make it more universal / more international. Suitable for UK and USA customers.

When labeled as "biscuit cookie," the term typically reflects a marketing or descriptive choice rather than a strict linguistic one. It often appears in the following contexts: Combining British and American English: The label may be used to appeal to a global audience, blending "biscuit" (British English) and "cookie" (American English) to clarify the product is the same type of sweet baked good familiar to both groups. Specific Product Characteristics: Sometimes, "biscuit cookie" refers to a product that combines the traits of both: A biscuit with a firmer, crisper texture (like shortbread). A cookie, which might be softer, chewier, or chunkier. For instance, a product might have the texture of a British-style biscuit but include ingredients (like chocolate chips) more common in American-style cookies. Cultural or Branding Quirk: Companies might use "biscuit cookie" to differentiate a product within a specific brand line, especially in global markets.

The company is Turkish. "Biscuit Cookie" is just the name they chose for this product so that it can be recognized internationally in British English and American English speaking markets.