APi Gateway, Lambda & Terraform: Get requests in json and respond in json

I provisioned a lambda function and api gateway resources in terraform, you know, the usual api gateway in front of lambda backend stuff. When I tried to return a response, i put a dictionary object in the body like this:

evt ={"pin": "some value"}

return {"statusCode": 200, "body": evt}

but it didn't work, i got an error saying malformed lambda response. Apparently the value of body needs to be a string. So it went through when I did this:

evt ={"pin": "some value"}

return {"statusCode": 200, "body": json.dumps(evt)}

So I need your help, how do i configure the API Gateway in terraform to make sure I can respond with a json/dictionary. I don't know why the event comes in as json (i checked) but I can't send back json.

These are the api gateway resources i have terraform: aws_api_gateway_rest_api aws_api_gateway_base_path_mapping aws_api_gateway_deployment aws_api_gateway_stage aws_api_gateway_rest_api_policy aws_api_gateway_resource aws_lambda_permission aws_api_gateway_method aws_api_gateway_integration aws_api_gateway_method_response aws_api_gateway_integration_response

PS: I don't want to use a swagger file.