Turn on a multi-functional pressure cooker (such as Instant Pot® and select the Saute function. Heat olive oil and add onion; cook until softened, about 7 minutes. Add garlic and cook for 1 minute more.
Combine butternut squash, vegetable stock, brown sugar, salt, black pepper and ginger in the pot. Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 10 minutes. Allow 10 to 15 minutes for pressure to build.
Release pressure carefully using the quick-release method according to manufacturer's instructions, about 5 minutes. Unlock and remove lid. Blend with an immersion blender until creamy.