PID temp controller, what are my best options for my scenario to obtain PID parameters ?

Hi, I've got a nichrome wire being heated in an enclosure by a 12V 5A source which is switched on/off by a PWM signal from Arduino that is fed to a MOSFET, there is also a K thermocouple inside the enclosure to measure the temperature, the objective is to maintain the temperature at 50°C using PI/PID controller(Arduino), the output of the PID controller will influence the PWM value(0-255) and that basically determines the average Voltage and Current delivered to the nichrome wire.

This is the Open Loop response I got at %20 PWM and modelled a 2nd order Transfer Function that resembles the experimental response. Now I did try the proportional-only controller and it does what I expected but I don't want to just randomly come up with I and D parameters.

What are my best options to obtain the PID parameters with what I got ?, I'd rather take a simulation based approach but I've never worked with Simulink and I don't know if it's possible to do this there.