Solution:

In order to allow single-line blocks in VSCode using Prettier - Code formatter extension, please take the following steps:

1. Enable stylelint integration by adding this in the VSCode Settings (JSON): "prettier.stylelintIntegration": true
2. Install stylelint and stylelint-prettier npm modules in your project directory. npm install stylelint stylelint-prettier --save-dev
3. Add a .stylelintrc.json file at the root of your project directory with the following code:

    {
        "plugins": ["stylelint-prettier"],
        "rules": {
            "block-closing-brace-newline-after": "always-multi-line",
            "block-closing-brace-empty-line-before": "never",
            "block-closing-brace-space-before": "always",
            "block-opening-brace-space-after": "always",
            "block-opening-brace-space-before": "always",
            "block-closing-brace-newline-before": "always-multi-line",
            "block-opening-brace-newline-after": "always-multi-line",
            "indentation": 4
        }
    }

You can add/customize more stylelint rules, see the entire list of rules here.

Took me a while to understand how to configure these options, if you're starting out with stylelint, I highly recommend you read its guidelines first.

Try adding this in your vscode's settings.json,

"[scss]": {
        "editor.defaultFormatter": "esbenp.prettier-vscode",
        "editor.formatOnSave": true
    },