Webpack combine multiple css files into single CSS file

I am attempting to set up a very simple webpack config file which would take all scss files within a project (including nested folders) and transpile and output to a single CSS file in the dist folder. I am using the MiniCssExtractPlugin to accomplish this

Sounds easy enough but i'm not having any luck setting it up, below are the contens of my webpack.config.js file:

const path = require('path');
const { resolve } = require('path');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

module.exports = {
    entry: './src/index.js',
    output: {
        filename: 'main.js',
        path: path.resolve(__dirname, 'dist'),
    },
    module: {
        rules: [
            {
                test: /\.css$/,
                include: resolve(__dirname, 'node_modules', 'react-toolbox'),
                use: [
                    MiniCssExtractPlugin.loader,
                    // 'style-loader',
                    {
                        loader: 'css-loader',
                        options: {
                            modules: true,
                            sourceMap: true,
                            importLoaders: 1,
                            localIdentName: '[name]_[local]_[hash:base64:5]'
                        }
                    },
                    // 'postcss-loader'
                ]
            },
            {
                test: /\.scss$/,
                use: ['style-loader', MiniCssExtractPlugin.loader, 'css-loader', 'sass-loader']
            },
            {
                test: /\.css$/,
                exclude: resolve(__dirname, 'node_modules', 'react-toolbox'),
                use: ['style-loader', 'css-loader']
            },
        ]
    },
    plugins: [
        new MiniCssExtractPlugin({
            filename: 'style.css',
        }),
    ],
};

Ny ideas where I'm going wrong?