Use Bicep to define a template spec

Set-AzBicepTemplateSpec

#requires -version 7
function Set-AzBicepTemplateSpec {
    [CmdletBinding()]
    param(
        #Template spec Resource ID to set
        [Alias('Id')][Parameter(ValueFromPipeline,ValueFromPipelineByPropertyName)]$ResourceId,
        #Path to the bicep file
        [Parameter(Mandatory)][String]$Path,
        #Optional Path to the UI Definition
        [String]$UIDefinitionPath = $($Path -replace '.bicep$','.ui.json'),
        [Parameter(Mandatory)][String]$Version,
        [String]$VersionDescription
    )
    begin {
        $ErrorActionPreference = 'stop'
        $bicepCmd = (Get-Command 'bicep' -ErrorAction SilentlyContinue) ?? (Write-Error 'bicep cli not found, ensure it is in your path')
    }
    process {
        $tempPath = "TEMP:bicep-$(new-GUID).json"
        $tempFile = New-Item $tempPath
        try {
            & $bicepCmd build $Path --outfile $tempFile
            $templateFile = Get-Item $tempPath

            $setTemplateSpecParams = @{
                TemplateFile = $templateFile
                ResourceId = $ResourceId
                Version = $Version
            }
            if ($VersionDescription) {$setTemplateSpecParams.VersionDescription = $VersionDescription}
            if ($UIDefinitionPath) {$setTemplateSpecParams.UIFormDefinitionFile = $UIDefinitionPath}

            Set-AzTemplateSpec @setTemplateSpecParams

        } catch {throw} finally {
            Remove-Item $tempFile
        }
    }
}