HttpApi timeout setting missing from SAM cloudformation template

My company is deploying lambda based serverless applications using the SAM cloudformation template format (which frustratingly has different syntax from the standard template). Using this format, I cannot find a way to set the "timeout in milliseconds" for an AWS::Serverless::HttpApi type gateway placed in front of the lambda. As it is, they default to 5 seconds which doesn't allow for cold start times or for requests that are longer than normal.

These services need to be controlled through the template as the development team doesn't have access to the console to adjust it through the web interface (company security policy).

How can we set this value during the cloudformation deploy or get it added as a property in the templates?