**Further simmering won’t reliably make it milder**, and evaporation can make the heat more concentrated. The beans may absorb some seasoning, spreading the heat more evenly, but they won’t remove it. [Seasoned Advice](https://cooking.stackexchange.com/questions/74737/does-chilli-get-milder-with-cooking)

For your curry, the most dependable fix is to **add more beans, tomatoes and cooked onion without adding chilli**. Another tin of drained cannellini beans is a good start; simmer briefly, then taste. Adding beans is also recommended in the [Bean Institute’s cookbook](https://beaninstitute.com/wp-content/uploads/2017/02/Northarvest_Bean_Cookbook_P2017pdf.pdf).

You can also stir in coconut milk or cream, or serve with plain yoghurt and rice to soften the perceived heat. Add yoghurt off the heat to help prevent curdling. [Seasoned Advice](https://cooking.stackexchange.com/questions/74737/does-chilli-get-milder-with-cooking/74738)