Basically:
brew install stunnel
openssl genrsa -out key.pem 2048
openssl req -new -x509 -key key.pem -out cert.pem -days 1095
This one will tunnel traffic from https://localhost/ to some remote non-HTTPS server, http://192.168.33.42/.
cat >> dev_https
pid=
cert=/usr/local/etc/stunnel/stunnel.pem
foreground=yes
debug=3
[https]
accept=443
connect=192.168.33.42:80
TIMEOUTclose=1
stunnel dev_https