[ViolaMum]

When I first wanted to learn to cook Indian food I was ever so fortunate to have a student whose parents were Indian and his mom was a fabulous cook. She would send me things to try during his lessons and then took me into her kitchen and showed me how she made some of her staples - basic curries and samosas. She used serrano chilis for heat - they're smaller and hotter than jalapenos, have a similar shape and just as readily available in US supermarkets. Habaneros and Scotch Bonnets are another option. (Habaneros are the ones that look like mini wrinkled bell peppers.) Generally speaking, the smaller the spicier.

The dairy in the recipe dulls the heat, which makes it tricky. You could try a spicier Garam Masala as well as hot paprika instead of sweet. (I tend to use smoked paprika, but my family is only a moderate spice crowd.)

A bit of Trivia - legend has it that Chicken Tikka Masala was actually created in the UK. (Glasgow, I think?)