Upsells with configurable options that can be added to the cart.
An extension that adds configurable options and an add-to-cart button to upsells in the frontend of your shop.
Please note this extension was designed for Magento 1.9.x
Please note you will need to integrate the upsells.phtml with your theme if needed. Do not forget to clear cache after installation.
For better functionality go to System -> Configuration -> Sales tab -> Checkout -> After Adding a Product Redirect to Shopping Cart -> No so the customer will stay on the page after having added an upsell to the cart.